JPH0647433A - Device for forming coil edge preliminarily - Google Patents

Abstract

PURPOSE:To preliminarily form a coil edge surely without taking a space by bending the coil edge part passing between two upper and lower pinch rolls in the upper direction previously before bending to feed the coil in the manufacture of a spiral steel tube. CONSTITUTION:The steel strip 1 comes to the pinch rolls 6 after it passes a welding machine 4 for joining coils and a milling device 5 for cutting a groove. The pinch rolls 6 clamp the steel strip 1 vertically to unwind the steel strip 1 and to send it to a forming part. The steel strip 1 is sent by the pinch rolls 6 into three rows of forming rolls 7 to be formed in a spiral state and a preceding side edge 8 and a succeeding other side edge 9 are welded as they thrust each other. An upper pinch roll 10 facing the coil edge part is worked in a convergent taper and a lower pinch roll 11 is worked in a divergent taper to form upper and lower pinch roll profiles which can form the coil edge part preliminarily in the upper direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil edge preforming apparatus for solving the problem of appearance quality due to the deformation of the coil edge portion which occurs in the forming of spiral steel pipe.

[0002]

2. Description of the Related Art Conventionally, in a spiral steel pipe, while a hot-rolled coil is unwound from an uncoiler, a pinch roll feeds the coil diagonally to a forming part and a welding part, and a spiral forming is performed with a forming roll. It is manufactured by welding. In general, the spiral steel pipe is formed by three-point bending. But,
When this three-point bending is performed, a phenomenon in which the coil edge portion sags compared to the coil central portion occurs. That is, as shown in FIG. 5, a phenomenon in which the left and right edge portions 15 of the steel strip 1 bend downward, that is, a so-called saddle-shaped deformation of a horse occurs. As shown in FIG. 6, the steel pipe 16 formed into a spiral shape and welded after the saddle-shaped deformation of the horse is in a peaking state in which the weld bead portion 17 is higher than other portions, as shown in FIG. As a product, it becomes a problem in terms of appearance quality.

[0003]

As a measure against this problem, a method of previously bending the coil edge in the opposite direction before forming, and disposing a forming roll directly below the coil edge,
A method for preventing the saddle-shaped deformation of the horse has been proposed. However, the former method requires equipment space,
In addition, the latter method has a problem in that the molding rolls may not be placed due to equipment restrictions.

[0004]

SUMMARY OF THE INVENTION As described above, it is an object of the present invention to solve the problems of the prior art and to provide an apparatus for reliably preforming coil edges without taking up space. The gist of the invention is (1) in the manufacture of a spiral steel pipe, the upper and lower two pinch rolls for coil feeding pass through the coil edge portions and are bent upward in advance before forming. Characteristic coil edge preforming device. (2) In manufacturing a spiral steel pipe, a portion through which a coil edge portion of two upper and lower pinch rolls for feeding a coil is made into a split roll of a flat portion and a curved portion, and the upper and lower curved portions are idle rolls. In addition, the coil edge preforming apparatus is characterized in that the idler roll is preliminarily bent upward before forming.

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a conceptual diagram showing a manufacturing process of a spiral steel pipe. As shown in FIG. 1, a steel strip 1 is unwound by an uncoiler 2 and flattened by a leveler 3, and then a coil joint welding machine 4 and a milling device 5 for groove cutting.
After passing through, reach the pinch roll 6. Pinch roll 6
Bears all the power for pinching the steel strip 1 from above and below, unwinding the steel strip 1 and feeding it into the forming part. The steel strip 1 is fed into the three rows of forming rolls 7 by the pinch rolls 6 and is formed into a spiral shape, and welding is performed so that the leading side edge 8 and the trailing other side edge 9 are butted against each other. Be seen. The spiral steel pipe is manufactured by continuously forming and welding the inner and outer surfaces in a spiral pipe making machine, and then cutting the pipe into a predetermined length by a traveling cutting machine (not shown) to produce a pipe.

FIG. 2 is a sectional view showing a bent state of the pinch roll according to the present invention. As shown in FIG. 2, an upper pinch roll 10 and a lower pinch roll 11 that hit the coil edge portion.
The upper pinch roll is processed into a tapered taper, and the lower pinch roll is processed into a divergent taper to form an upper and lower pinch roll profile that can preform the coil edge in the upward direction. To do.

FIG. 3 is a diagram showing a pinch roll profile according to the present invention. As shown in FIG. 3, regarding the bending preforming amount, since the deformation amount of the saddle-shaped deformation of the horse described above varies depending on the thickness, width, bending curvature, strength, etc. of the coil, naturally the preforming amount for bending the upper surface in advance. It is also necessary to change the pinch roll profile by changing the radius of curvature continuously instead of changing the radius of curvature to a single radius and shifting the pinch rolls according to the predetermined bending amount. It is what

Further, FIG. 4 is a sectional view showing a split roll of the pinch roll according to the present invention. As shown in FIG. 4, the flat portion roll 12, the curved portion upper roll 13, and the curved portion lower roll 14 are divided rolls, so that the coil passing occurs due to the different rotational peripheral speeds of the flat portion roll and the curved portion roll. It prevents the destabilization and the occurrence of scratches. That is, in the pinch roll, a difference in rotational peripheral speed occurs between the center portion and the edge portion of the pinch roll, and as a result, the coil passing plate may become unstable, and further, the steel strip may be scratched. In order to prevent this, according to the present invention, the flat portion and the curved portion are divided into rolls, and the curved portion is idled to idle rotate the coil threaded plate at the edge portion, thereby destabilizing the coil threaded plate. The occurrence of scratches and the like is reduced.

[0009]

【Example】

Example 1 1850 mm width, 16 m unwound from uncoiler
A steel strip of m thickness is trimmed, spiral forming and inner and outer surface welding are sequentially performed to manufacture a spiral steel pipe with a diameter of 800 mm. When manufacturing a spiral steel pipe with a diameter of 800 mm, a taper is used for the upper pinch roll where the coil edge passes and Is a pair of pinch rolls with a thickened taper shifted to the optimum position and the coil edge portion is bent upward, but the leading side edge and the following other side edge are butted against each other.
Welded from the inner and outer surfaces with a predetermined current to make a spiral steel pipe. As a result, peaking at the weld bead portion, which has been conventionally seen, was not observed at all, and it was possible to manufacture a spiral steel pipe having an extremely excellent appearance quality.

Example 2 In the method for manufacturing a spiral steel pipe under the same conditions as in Example 1, the tip ends of the upper and lower pinch rolls are divided rolls, and the upper pinch rolls of the divided rolls are tapered. A spiral steel pipe was produced by a pinch roll having a pair of idled dividing rolls with a tapered taper on the lower dividing rolls. As a result, the steel strip is passed through in a very stable state, there is no damage to the steel strip, and there is no peaking at the weld bead part that has been seen in the past. We were able to manufacture steel pipes.

[0011]

As described above, by carrying out the present invention, the coil threading is carried in an extremely stable state, and the coiling is carried to the forming step without any scratches on the steel strip. , The deformation of the coil edge part that occurred in the conventional manufacturing of spiral steel pipes is eliminated, as a result the problem of appearance quality due to peaking is solved, and it becomes possible to manufacture spiral steel pipes with extremely excellent appearance quality. became.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a manufacturing process of a spiral steel pipe.

FIG. 2 is a sectional view showing a bent state of a pinch roll according to the present invention.

FIG. 3 is a view showing a pinch roll profile according to the present invention.

FIG. 4 is a sectional view showing a split roll of a pinch roll according to the present invention.

FIG. 5 is a conceptual diagram showing a phenomenon in which left and right edge portions of a steel strip bend downward in a conventional technique.

FIG. 6 is a conceptual diagram showing a state where peaking occurs in a weld bead portion of a conventional spiral steel pipe.

[Explanation of symbols]

 1 steel strip 2 uncoiler 3 leveler 4 coil joint welding machine 5 milling device 6 pinch roll 7 forming roll 8 leading coil side edge 9 trailing coil side edge 10 upper pinch roll 11 lower pinch roll 12 flat part roll 13 on curvature part Roll 14 Curvature part lower roll 15 Left and right edge part 16 Steel pipe 17 Weld bead part

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toshio Hirokawa 1 Kimitsu, Kimitsu-shi, Chiba Nippon Steel Corp. Kimitsu Steel Co., Ltd.

Claims (2)

[Claims] 1. A coil characterized in that, in the manufacture of a spiral steel pipe, the coil edge is preliminarily bent upward before forming by the portions through which the coil edge portions of the upper and lower two pinch rolls for feeding the coil pass. Edge preforming device. 2. In the manufacture of a spiral steel pipe, a portion through which a coil edge portion of two upper and lower pinch rolls for feeding a coil passes is used as a split roll of a flat portion and a curved portion, and the upper and lower curved portions are formed. A coil edge preforming apparatus, characterized in that the coil edge is preliminarily bent and shaped before forming by an idle roll before forming.