JP2994159B2 - Steel pipe shaping method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention does not require roll change,
The present invention relates to a method of forming a steel pipe having a function of improving roundness at an arbitrary outer diameter.

[0002]

2. Description of the Related Art Conventionally, the narrowing of a steel pipe 1 is performed by adjusting upper and lower rolls 2a and 2b or rolls 2a to 2d divided in the circumferential direction of the pipe as shown in FIG. A method of performing a fixed shape using a roll having a hole diameter smaller than the pipe diameter is used.

In a conventional drawing roll, it is possible to change the drawing ratio by moving the roll in the radial direction.
However, the roundness of the pipe 1 deteriorates (see FIG. 2).
Is the problem. Prior art is disclosed in Japanese Patent Application Laid-Open No. 64-2709.
As described in Japanese Patent Application Laid-Open Publication No. H10-260, it has been known that after a strong pressure is applied from the longer diameter side of an elliptical shape, the diameter is reduced to a circular shape and the shape is reduced.

[0004]

In the conventional opposed-type drawing roll method, the inner surface position of the roll hole die in the radial direction does not have a fixed drawing position in the radial direction of the pipe. This indicates polygonization, and the roundness is degraded.
If an attempt is made to increase the drawing rate beyond the additional drawing amount that matches the reference roll position, the roundness will deteriorate in proportion to the additional drawing amount. If the amount of aperture is too small, the roundness also deteriorates. That is, it is not possible to manufacture a pipe with high roundness unless the roll is replaced with a roll using a hole shape that matches the dimension after drawing. An object of the present invention is to easily manufacture a steel pipe having a high roundness with the same roll without changing the roll even if the pipe size changes in a fixed form.

[0005]

SUMMARY OF THE INVENTION The gist of the present invention is to arrange a tiltable concave roll having a roll radius of curvature larger than a plurality of pipe radiators radially with respect to a steel pipe, and to revolve around the steel pipe without driving the roll. Is possible, the roll is expandable and contractible in the radial direction of the pipe, and after the roll is arranged at a predetermined position,
A method for forming a steel pipe, wherein the roll is rotated and revolved, and the steel pipe is formed through the steel pipe.

In order to make it possible to change the amount of drawing with the same roll, the position of the roll must be changed in the radial direction of the pipe. In order to make the position of the roll uniform in the radial direction,
This is possible by rotating the pipe in the circumferential direction with respect to the center of the pipe. In this case, the influence of the roll shape of two or three rolls on the pipe shape will be considered.

When the forming roll is a convex roll, the pipe and the roll are almost in linear contact. To make the contact position of the pipe with the roll in the radial direction constant, the roll is rotated in the pipe circumferential direction, Since it is necessary to give uniform deformation in the circumferential direction, the pitch of the spiral trajectory of the roll cannot be made large.

However, when a concave roll having a radius of curvature larger than the pipe radius is used as the forming roll, the pipe and the roll have surface contact by inclining the roll in the axial direction so that the pipe and the roll have the same curvature. In particular, the contact width in the circumferential direction can be significantly increased, and at the same time, the contact width increases.

This makes it possible to increase the crossing angle between the pipe axis and the roll axis, thereby improving the speed of forming at the same roll rotation speed. In addition, by expanding and contracting the roll position in the radial direction of the steel pipe, it is possible to form pipes having different outer diameters. In FIG. 3, the intersection angle between the roll and the pipe is changed at a radius of curvature R = 40 mm, which is larger than the pipe radius at φ100.
The positional relationship of a pipe standard that is almost appropriate at φ40 at 5 degrees is shown, but the pipe curvature and the hole-shaped curvature are almost the same.

The reason for the non-drive is that the convex roll has a small crossing angle between the roll rotation axis and the pipe, so that a rotation force for forming in the circumferential direction is required. , The roll rotation speed and the helical rotation are naturally synchronized by pushing the steel pipe. Therefore, the present invention can be easily applied to the conventional electric resistance welded tube forming line without adding a complicated drive system for synchronizing the roll rotation and the revolution speed by control.

Regarding the versatility of the rolls, there is a limit to the number of rolls that can be arranged in the same cross section because of the interference between the rolls and the interference between the roll supporting portions. In this case, a two-roll system can be used, and a three-roll system can be used up to twice.

[0012]

EXAMPLE An apparatus shown in FIG. 4 was manufactured and molded as an example of the present invention. The apparatus comprises a support 3 for changing the intersection angle between the roll 2 and the pipe 1 and the roll, a radial position, and a rotary support 4 on which the roll can revolve. Outer diameter D = 2
FIG. 5 shows the molding results of pipes having different outer diameters of 0 (mm) and an outer diameter D = 40 (mm). In this embodiment, the same roundness as that of the conventional opposed-type drawing method can be ensured even if the drawing amount is increased and the outer diameter size is different.

[0013]

As described above, the shaping method of the present invention is industrially useful as a means capable of shaping with good roundness without replacing the shaping means such as rolls for pipes of various sizes. It can bring various effects.

[Brief description of the drawings]

FIG. 1 is a schematic view of a conventional drawing device, showing two rolls and four rolls.

FIG. 2 is a schematic view of deterioration of roundness in a conventional method with an appropriate aperture and a case other than an appropriate aperture.

FIG. 3 is a schematic diagram showing appropriate roll positions for forming when the diameter is small and when the diameter is large.

FIG. 4 is an example of an apparatus of the method of the present invention.

FIG. 5 is a diagram showing the outer diameter of a pipe when it is fixed by the apparatus shown in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pipe 2 Roll 3 Variable angle roll support 4 Radial expansion / contraction device 5 Revolution device

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Claims (1)

(57) [Claims] 1. A plurality of tiltable concave rolls having a roll radius of curvature larger than a radius of a pipe are arranged radially with respect to a steel pipe to enable self-revolving motion without driving a roll. A method for forming a steel pipe, wherein the steel pipe is formed while being allowed to expand and contract in the radial direction, the roll is arranged at a predetermined position, and then the roll is rotated and revolved, and is passed through the steel pipe.