JPS62166027A - Forming roll for pipe mill - Google Patents

Abstract

PURPOSE:To manufacture the resistance welded tube of various kinds of diameters and thicknesses without changing a forming roll by changing the abutting direction of the forming roll of a strip steel at the resistance welding steel tube manufacturing time in accordance with the strip steel width and the necessary number of forming stages. CONSTITUTION:The pipe of small bore upto that of large bore and yet a thick strip steel are formed in circular cross section with a single form-roll in case of manufacturing a resistance welded tube by welding its both end parts by forming a strip steel 10 in a circular shape from semi-circular shape. Since the strip steel 10 is formed in circular shape by the upper and lower roll 5, 18 in case of this forming the rolling face is formed to coincide with the curve face at the upper side of the lower forming roll 5 in the end face bending of the strip steel with width and to the upper side curve face of the lower forming roll 5 in the end part bending of the strip steel with narrow width so that one part of the whole part of the cross sectional curve of these roll faces is coincided with the pre-set curve of the strip steel end part in each roll flower of the steel pipe of various outer diameters. The strip steel is formed in the aiming diameter by moving the forming roll so that the necessary curve face comes to the prescribed position according to the bore of the resistance welded steel tube, namely the width of the steel strip.

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. Suitable for manufacturing steel pipes of various nominal diameters and wall thicknesses from small diameter pipes to large diameter pipes, with a single forming roll used in each forming stage, without replacing the forming rolls. Even though the roll can be used in a very wide range, for example, when used as a forming roll for bending the ends of the band, it is possible to form the ends of the band sufficiently and reliably. As a forming roll at the center of the steel, it can make line contact with the bent part of the end of the steel strip, and has excellent roll surface pressure reduction and formability into the required circular shape, and is also effective in correcting insufficient or defective end bending in the previous stage. The present invention relates to a forming roll for a pipe mill that can be widely used and also has the effect of preventing rolling of the material to be formed.

BACKGROUND TECHNOLOGY Straight seam welded steel pipes are currently manufactured using so-called continuous roll forming, in which a steel strip is continuously formed 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 numbers of products.

As shown in Fig. 10, pipe making by continuous roll forming is roughly divided into the forming area for the ends of the steel strip, the forming area for the center of the steel strip, and the reducing area. Initial forming from bending the end of the steel strip to a semicircle is performed using a cluster (see the same figure), and then using a non-driven side roll cluster (see the same figure) and/or a horizontal roll, the strip is formed into an almost circular shape. After forming, angle adjustment, reduction, final forming, and centering of the edge surface are performed using so-called fin pass rolls (Fig. d), and the welding process 1v is started using squeeze rolls.

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 edge stretch that occurs when forming thin-walled pipes, cage rolls are used. A cage forming method in which a large number of small rolls with flat surfaces are arranged is also used.

In all of these conventional continuous roll forming methods, the initial stage of forming is mainly semicircular, which is the most difficult to form.
Although there are many splinter backs after passing through the rolls due to insufficient bending of the ends of the steel strip, which determines the roundness of the pipe and the quality of the welding process, forming By increasing the number of stages and forming the center of the steel strip in the next forming area without completely bending the band, the poor formability in the initial and middle stages of forming is corrected in the reducing area. It is made up of thoughts.

Therefore, an increase in the amount of molding in the reducing 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 the accuracy and manufacturability of the product and the economy 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 can be carried out sufficiently at the stage of bending the ends of the strip, or At this stage, we compensate for the lack of edge bending,
There has been a strong need for a molding method or a molding device that can prevent angular formation.

Generally speaking, as mentioned above, the production of welded steel pipes by continuous roll forming requires the use of forming rolls suitable for forming the required diameter and wall thickness, and the forming roll arrangement according to the diameter, and the need for forming the steel strip to be formed. It is necessary to replace the forming rolls depending on the width, and it is not desirable from the viewpoint of manufacturing efficiency to prepare and replace a very large number of forming rolls for each required diameter. It has been used for the mass production of various products, but today there is a need to efficiently manufacture a wide variety of products using a single machine. A roll forming method or forming apparatus is needed.

Also, in double radius molding, if the diameter changes,
Since the curvature of the end bending changes, when sharing a roll,
It is not possible to roll down the bent end part, and a part of the circular part is rolled down while making point contact with a straight roll or a roll with a relatively large radius of curvature, which deteriorates the formability into a circle and tends to cause angularity. There was a problem.

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

Purpose of the Invention In view of the current situation, the present invention has been made to form a welded steel pipe by continuous roll forming, in which the center part of the steel strip from bending the end of the steel strip to the subsequent approximately circular shape can be easily formed without replacing the forming rolls. With one forming roll, it is possible to form steel pipes of a wide range of diameters and wall thicknesses, from small diameter pipes to large diameter pipes, and it is also possible to reliably bend the ends of the steel strip, or to compensate for insufficient end bending when forming the center part. The purpose of this product is a forming roll that can be widely used in pipe mills and can prevent angular formation and produce steel pipes with excellent shapes.

Structure and Effects of the Invention The present invention enables the contact direction of the forming rolls to be changed in accordance with the width of the steel strip to be formed and the required forming stage in forming the forming area of each part of the steel strip in the manufacture of pipes by continuous roll forming. In order to form on a part or the entire surface of the roll surface, part or all of the cross-sectional curve of the roll surface is made to match 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. The forming roll for a pipe mill is characterized in that it has a cross-sectional curve consisting of an expansion curve based on a preset polygon.

By using the forming roll according to the present invention, for example, in forming the forming area of the end of the steel band, both ends of the steel band are formed by upper and lower sets of forming rolls each having the expansion curve as a cross-sectional shape, When forming this in one stage or in multiple stages, the interval between the pair of forming rolls at both ends of the steel strip is changed according to the width of the steel strip, and if necessary, rolls that raise the center part of the steel strip upward are used. At least the rolling direction of the upper forming roll of each forming roll set is changed, and forming is performed on a part or the entire surface of the elongation curve of the forming roll cross-sectional shape set in advance, depending on the width of the strip to be formed and the required end bending stage. The method for forming the end of a steel strip in a pipe mill can be carried out.

In other words, the method of forming the ends of a steel strip using forming rolls according to the present invention can be used to form steel pipes of various diameters and wall thicknesses over a wide range from small diameter pipes to large diameter pipes using a single forming roll without replacing the forming rolls. It is possible to form the ends of the steel strip suitable for the production of
Formability in the initial stage of molding in a pipe mill can be significantly improved, and defects at the ends are reduced.

Furthermore, by using the forming roll according to the present invention,
In forming the forming area of the center of the steel strip after faceting the ends of the steel strip, the bent end portion of the steel strip is pressed with a side roll whose cross-sectional shape is the expansion curve, and the side roll is rolled in one or multiple stages. When forming the steel strip into a substantially circular shape by placing the side rolls in It is possible to perform a forming method for the center of the steel strip in a pipe mill in which the center part of the steel strip is formed on a part or the entire surface of the expansion curve of the side roll cross-sectional shape set in advance. A forming method can be implemented in which an intermediate roll that contacts the center from above and/or a horizontal roll that contacts the center of the steel strip from below are used.

That is, the method for forming the center of a steel strip using forming rolls according to the present invention uses only the side rolls having the above-mentioned shape, or the upper intermediate roll and/or the lower horizontal roll that can come into contact with the center of the steel strip by fjf. By using a single forming roll, it is possible to form the center of a steel strip that is suitable for manufacturing steel pipes of a wide range of diameters and wall thicknesses, from small diameter pipes to large diameter pipes, without replacing the forming rolls. In addition, it is possible to correct the side face of the strip steel end, reduce the influence of springback, and significantly improve the formability in the initial and middle stages of forming in a pipe mill. It reduces the amount of molding in the area and enables continuous roll forming with excellent molding distribution and formability.

Furthermore, by using the forming rolls according to the present invention in all forming stages of a pipe mill, there is an advantage that the number of forming rolls can be reduced and there is no need to replace the forming rolls. Horizontal rolls, side rolls, upper and lower intermediate rolls at each stage of forming and/or forming area of the center of the strip.

Alternatively, it can be used as a cage roll, combined with various conventional forming rolls, or used alternately with conventional forming rolls at each forming stage, etc., as appropriate.

DISCLOSURE OF THE INVENTION BASED ON DRAWINGS In the present invention, for example, a forming roll for bending the end of a strip steel is formed using one forming roll as shown in FIGS. 7 and 8.
Part or all of the cross-sectional curve of the roll surface of the upper and lower forming rolls + 5) (1B) is set in advance to enable bending of the steel strip ends of large and small diameter pipes. In order to match the curve of the end of the steel strip (10) to be drilled into the roll flower, the end of the wide strip 1M (10) is bent in the drawing.
The curved surface of the lower side of the lower forming roll (5), and when bending the end of the narrow band l (10), the roll surface is made to match the upper curved surface of the lower forming roll (5) as required. The forming rolls are moved so that the required curved surface is in a predetermined position according to the diameter, that is, the width of the steel strip.The movement of a pair of upper and lower forming rolls in the width direction of the steel strip that bends the ends of the steel strip. Of course, it is necessary to change the direction of the roll surface at least only for 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. , so that part or all of the cross-sectional curve of the roll surface of the forming roll (29) disposed on the side matches the curve of the end of the steel strip in each roll flower of various outer diameter steel pipes set in advance. As shown in Fig. 4, in the center forming of the wide strip m (10), the center part of the narrow band m (10) shown in Fig. 5 is formed on the lower curved surface of the forming roll (29). In forming, forming rolls (
29) No roll surface that matches the upper curved surface,
The forming roll is moved so that the required curved surface is in a predetermined position according to the required diameter, that is, the width of the steel strip.

It can also be used as an upper intermediate roll that contacts the center of the steel strip from above, and with the same concept, the intermediate roll (10
), a part or all of the cross-sectional curve of the roll surface of the band vA in each roll flower of steel pipes with various outer diameters set in advance.
(10) Create a two-part roll that can approach and separate in the width direction of the steel strip so as to match the curve at the center, so that the required curved surface is at a predetermined position according to 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.

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. The idea is to match the edge 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 of the many types of circular arcs necessary for forming the ends of various steel strips is formed on the roll surface. As a result of various studies, we found that a so-called expansion curve is appropriate.

In other words, conventional forming rolls with curved surfaces such as double radius cannot be used as common rolls, but if the roll surface is given an expansion curve based on a circle,
Although it can be used as a forming roll with a much wider range of uses,
As roughly 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 form pipes of dozens of different diameters, we found that the required radius and length described above are different for each roll. In order to obtain a continuous arc surface that includes all of the many types of arcs, it must be an expansion curve based on polygons assuming the arcs as shown in Figures 1, 2, and 3. This discovery was made and this invention was completed.

The roll surface of the forming roll is shown in FIGS. 1 and 2.

To explain in detail with the upper and lower rolls in FIG. 3, the roll surface of the forming roll has a polygonal shape set in advance according to the required diameter type, wall thickness, and rough edge bending stage. The cross-sectional shape of the roll surface is an expansion curve based on α1.α2゜α3 in the drawing, and the roll surface based on this specific expansion curve is used to roll form small to large diameter pipes. The curve of the edge of the steel strip or the curve of the center of the steel strip of roll flowers of steel pipes of various outside diameters and wall thicknesses in , and the curve of the center of the steel strip can be brought into contact and pressed.

In general, it has been found that in the forming roll according to the present invention, springback at the end of the steel strip can be prevented by making the cross-sectional shape of the roll surface an expansion curve based on a preset polygon. To explain the mechanism in detail, in general, even if forming is performed with a roll having a curved surface of a constant curvature, the characteristics of the material and the plate thickness will be affected.

Although it varies depending on the curvature, the plate bent along the roll curved surface during rolling is formed into a continuously changing curvature due to springback after passing through the forming rolls.

In other words, in a forming roll having a curved surface with 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. It can be said that molding with a constant curvature is practically impossible.

However, if the curved surface has a smaller radius as it approaches the end of the steel strip, even if springback occurs, bending to a required constant radius becomes possible. As shown in FIGS. 1, 2, and 3, the cross-sectional shape of the roll surface of the forming roll of this invention is an expansion curve based on a preset polygon, so that The closer the end is to the curved surface, the smaller the radius of the curved surface, which has the effect of forming the end of the steel strip into a curved surface with a constant radius.

Therefore, even if sufficient end bending can be carried out in the strip steel end bending process, or even if the forming process of the center part of the steel strip is started without sufficient end bending in the steel band end bending process, Since the side roll according to the present invention has the above-described configuration and effects, it is possible to form the central part of the steel strip and at the same time compensate for the lack of a mark at the end of the band, and it can be formed 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 a preset polygon, so that it is close to the end of the steel strip. Since it is possible to form a curved surface with a smaller radius, the side rolls can make line contact with the bent end of the strip so as to hold it in place, preventing rolling of the material to be formed, and 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 roll according to the present invention can be carried out by using only the forming roll of the above shape or by using various combinations of conventional forming rolls, without replacing the forming roll. With this forming roll, it is possible to form pipes that are suitable for manufacturing steel pipes with a wide range of nominal diameters and wall thicknesses, from small diameter pipes to large diameter pipes, and can compensate for the bending of the ends of the steel strip, eliminating the effects of springback. It is possible to significantly improve the formability in the initial and middle stages of forming in a pipe mill, and reduce defects at the end, reducing the amount of forming in the subsequent reducing area, resulting in a continuous roll with excellent forming distribution and formability. Can be molded.

In the forming roll of the present invention, preferably, 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 are set in advance according to the width of the steel strip to be formed and the required forming stage. It is preferable to have a configuration 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 a part or the entire surface of the companion curve of the roll cross-sectional shape can come into contact with the end of the steel strip.

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 is also applicable to
It can be applied to forming rolls for forming pipes of various metal two-alloys including steel strips.

Furthermore, the specific elongation curve constituting the roll surface, which is a feature of the forming roll according to the present invention, can be used in various forming methods depending on the type of rolls applied, such as upper and lower rolls, side rolls, lower horizontal rolls, upper and lower intermediate rolls, etc. It may be selected as appropriate depending on various conditions such as the number of stages, required 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 device consists of a regular roll stand with a U-shaped roll stand (2M21) set upright on a base (1) at predetermined intervals, and a lower roll shaft (3) and an upper roll support shaft (4) arranged between them. .

On the lower roll shaft (3), a pair of lower rolls (5 x 5) and two divided intermediate rolls (6) (6) arranged 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 the drive shaft here.

The upper roll support shaft (4) supports a pair of non-driven upper rolls (18
) (18) vertically, and the lower roll shaft (3)
The spindle body is attached to the screw shaft (11) screwed onto the upper end of the roll stand (2) so that the facing distance can be adjusted to cope with the thickness of the band m (+01) and the amount of rolling down can be increased or decreased. (12) is connected and held by the 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 set by @.

A saddle-shaped upper roll holding seat (16) is attached to the rail (14) via a slide bracket (15) that can be fitted and slid on the rail (14), and its head is connected to the pair of beam members (13). It is held vertically by entering the space between the two.

The upper roll holding seat (16) has a downwardly facing inner surface forming a cylindrical seat surface (17) facing toward the rail (14). Additionally, a U-shaped bearing member (19) that pivotally supports the upper roll (18) is provided.
) is provided with a fan-shaped contact member that comes into contact with the cylindrical seat surface (1Y), and the fan-shaped support fixed to the upper roll support seat (16) is a member, and the fan-shaped contact member that comes into contact with the cylindrical seat surface (1Y) is a member that is attached between the cylindrical seat surface (17). It is slidably held in the

A fan-shaped tooth surface is provided on the upper surface of the bearing member (19), and the bearing member (19) of the upper roll (18) is driven by a gear.
) moves in an arc, and the roll surface of the upper roll (18)
The structure is such that the direction of contact with I(10) can be changed in the width direction.

Further, in the drawings, a nut member fixed to the head of each saddle-shaped upper roll holding seat (16) is moved by rotation of a screw shaft so that the left and right upper rolls (18) approach and separate from each other.

On the other hand, the lower roll +5X5) and the intermediate roll <6X6) are positioned on the lower roll shaft (3) via a spacer (sword) to adjust their position with respect to the steel strip (10), as shown in the previous). The upper roll (1B) (18) is also configured so that the width direction and the contact direction of the roll surface can be changed with respect to the steel strip (10).

Rough, upper roll (18) (1B), lower roll (5X5
) and intermediate rolls (6X6), each roll surface has the required steel pipe outer diameter width, for example, from 89.1φ to 193φ.
Assuming that various steel pipes will be formed, the cross-sectional shape is an expansion curve based on a preset polygon so as to match the curve of the end of the steel strip in each roll flower of steel pipes with various outside diameters. Consists of forming rolls.

The forming apparatus according to the present invention having the above-mentioned configuration can be used, for example, when forming a relatively large-diameter steel pipe to form a steel strip at both ends of a steel strip (10) of a required width, as shown in FIG. A pair of forming rolls, that is, a pair of upper rolls (1
8), change the interval according to the width of the steel strip (10) so that the lower roll (5) set is located, and then add the upper roll (18)
) by changing the direction of contact with the rolling direction band &M (10),
(10) Depending on the width and the required end bending stage, i.e. whether it is completed in one stage or divided into multiple stages,
A strip steel (10
) into the desired shape.

In this case, an intermediate roll (6) is used to raise the central part of the steel strip and improve formability at both ends.
The interval between the pair of intermediate rows 6×6) is also appropriately selected depending on the strip width and the forming stage.

In addition, in the case of the smallest diameter of the assumed diameter, as shown in FIG.
, 8) Change the contact direction of (18) to the opposite direction from the previous one,
The strip steel (10
Shape the ends into the desired shape.

As described in detail, the forming apparatus according to the present invention is capable of forming the end of a strip steel suitable for manufacturing steel pipes of various column diameters ranging from small diameter pipes to large diameter pipes with a single forming roll without replacing the forming rolls. There is a gap between the parts.

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

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

A side roll support (25) consisting of a box body and pivoting the non-driven side roll (29) so as to be able to move in a predetermined arc is slidably placed on the slide frame (24),
A nut member (28) is fixed to the bottom of the slide frame (24), and is screwed onto a screw shaft (27) disposed within the slide frame (24) and connected to the column frame (23). As the screw shaft (27) is rotated by the drive of motors (not shown) built in both sides of the slide frame (24) to be fitted, the side roll support (25) is rotated in the axial direction, that is, in the width direction of the strip steel. The structure is such that the side rolls (29) move in the width direction of the steel strip, and the pair of left and right slide frames (24) in the drawing
A screw shaft (28) is engaged with a nut member (28) fixed to the bottom of each support (24) so that the screws approach and separate from each other.
) are opposite to each other.

The upper intermediate roll (30) consists 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 a slide frame (24) that can move up and down.
To deal with the thickness of the strip steel, adjust the opposing distance.
In addition, in order to increase or decrease the contact m, the shaft support 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), and the roll stand (22) It is configured so that it can be moved vertically by being held between the two.

The roll holding seat (33) fixed in the side roll support (25) has a cylindrical seat surface (
34). The cylindrical seat surface (
A fan-shaped abutment member is provided which abuts on the roll holding seat (34), and the fan-shaped support fixed to the roll holding seat (33) is a member that is slidably held between the cylindrical seat surfaces.

Further, a fan-shaped tooth surface is provided on the upper surface of the bearing member (35, not shown), and the side roll (2
The bearing member 9) moves in an arc, and the roll surface of the side roll (29) can change the direction of contact with the edged steel strip in the width direction.

Roughly, a pair of side rolls (29), an upper middle roll (
30), each roll surface has the required steel pipe outer diameter width,
For example, assuming that various steel pipes from 89.1φ to 193φ are to be formed, a preset polygon is created to match the curve of the bent end or center of the strip steel in each roll flower of steel pipes with various outside diameters. It consists of a forming roll whose cross-sectional shape is a basic expansion curve.

The forming apparatus according to the present invention having the above configuration is used, for example, to target the ends of a steel strip in forming a relatively large diameter steel pipe, as shown in FIG. (29), the interval between the upper intermediate rolls (30) is changed according to the width of the strip so that the set of upper intermediate rolls (30) is located at the center of the strip, and the rolling direction of the side rolls (29),
The direction of contact with the strip steel is changed, and the expansion curve of the preset roll surface cross-sectional shape is The required curved surface portion The curved surface portion contacts and embraces the bent end portion of the steel band to form 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 applies to the relatively early and middle stages of the forming process of the center of the steel strip, as shown in Figures 4 and 5, in which the roll surface of the side rolls (30) changes from upward to sideways. 172 from the stage, i.e., the stage equivalent to tantoge
It is about 273 yen. Roughly speaking, when forming from this stage to a substantially circular shape, a lower horizontal roll (36) that contacts the center of the steel strip from below is used instead of the upper intermediate roll (30), as shown in FIG. By arranging the side rolls (29) so as to be able to move up and down, the rolling direction can be changed in stages from the horizontal direction to the downward direction. It is always held in the side rolls (29) that match the bending shape and is formed into the desired circular shape.Although the side rolls (2) can be used widely, it has excellent formability. I understand.

As described in detail, the forming apparatus according to the present invention is capable of forming steel strips suitable for manufacturing steel pipes of a wide range of column diameters from small diameter pipes to large diameter pipes using a single forming roll without replacing the forming rolls. I can do it.

As shown in Fig. 1, the side roll surface has a cross-sectional shape of an expansion curve based on a preset polygon, so the closer it is to the end of the steel strip, the smaller the radius of the curved surface is. Since it is possible to do this, Obi FJA@ with a side roll
The bending part can be held in line contact to prevent rolling of the material to be formed, and it is also possible to correct the bending of the end of the steel strip, reducing the influence of springback, which can be used in the early and middle stages of forming in pipe mills. The moldability of the material can be significantly improved.

[Brief explanation of drawings]

FIGS. 1, 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. 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. FIG. 10 is an explanatory diagram 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, 1
3... Beam member, 14... Rail, 15... Slide bracket, 16... Upper roll holding seat, 17...
Cylindrical seat surface, 18... Upper roll, 19... Bearing member,
21... Base, 22... Gate-shaped stand, 23...
Column frame, 24... Slide frame, 25... Side roll support, 26... Hydraulic jack, 27... Screw shaft, 28... Nut member, 29... Side roll, 3
0... Upper intermediate roll, 31... Screw shaft, 32
...Shaft support material, 33...Roll holding seat, 34...
Cylindrical seat surface, 35...Bearing member, 36...Lower horizontal roll. Figure 10 (α) (b) (c) (d)
Figure 7 Figure 3

Claims (1)

[Scope of Claims] 1. In forming the forming area of each part of the steel strip in the manufacture of pipes by continuous roll forming, the contact direction of the forming rolls can be changed according to the width of the steel band to be formed and the required forming stage. In order to form on part or all of the surface, part or all of the cross-sectional curve of the roll surface matches the curve of the required part of the strip steel of each roll flower of various outer diameter steel pipes in the forming area, A forming roll for a pipe mill characterized by having a cross-sectional curve consisting of an expansion curve based on a preset polygon. 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.