JPH05220507A - Method for forming steel tube - Google Patents

Abstract

PURPOSE:To provide a method for forming a steel tube with an arbitrary outside diameter and at an arbitrary drawing rate without necessitating roll change in the drawing/forming stage of an electric resistance welded tube. CONSTITUTION:Plural rolls 2 are radiately arranged to a steel tube, rotating force is added to the rolls themselves with hydraulic motors 3 and also the respective rolls are made to be freely expanded/contracted in the radial direction of the steel tube with radial direction expanding/contracting devices 5. This device consists of revolving devices 6 for assisting the revolution of roll and preventing circumferential rotation of the pipe and rotary hydraulic valve devices 7 with which the rotating force of roll can be transmitted even when it is revolved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention eliminates the need for roll replacement.
The present invention relates to a method for shaping a steel pipe having a function of squeezing a pipe with an arbitrary outer diameter and an arbitrary drawing ratio.

[0002]

2. Description of the Related Art Conventionally, the diameter of a steel pipe 1 is regulated by the upper and lower rolls 2a and 2b or the rolls 2a to 2d divided in the circumferential direction of the pipe as shown in FIG. In order to improve the degree, the method of drawing using a roll having a hole diameter smaller than the diameter of the pipe on the inlet side is used.

However, in the conventional squeezing roll, it is possible to change the drawing ratio by moving the roll in the radial direction of the pipe, but the roundness of the pipe 1 becomes poor (see FIG. 2). When the size of the pipe changes, it is necessary to change to a hole type that matches the outer diameter size of the pipe. As a prior art, it is known that, as disclosed in Japanese Patent Laid-Open No. 64-2709, the diameter is reduced into a circular shape after being strongly pressed from the elliptical major axis side.

[0004]

In the conventional opposed-type squeezing roll method, since the inner surface position of the hole die in the radial direction of the pipe does not have a constant decreasing position in the radial direction, the reference roll position indicates the polygonal shape. If the aperture ratio is further increased, the roundness deteriorates in proportion to the additional aperture amount.

That is, since only a roll hole type suitable for the outer diameter of the pipe after drawing can be used, the roll having a high circularity must be used unless the roll is changed according to the hole type suitable for the size after drawing. I can't get it. An object of the present invention is to easily manufacture a steel pipe with an arbitrary drawing ratio and a high roundness by the same roll without changing the roll even if the outer diameter size of the pipe is changed in the regular drawing. .

[0006]

SUMMARY OF THE INVENTION The gist of the present invention is to dispose a plurality of rolls radially on a steel pipe so that the rolls themselves have a rotation force and each roll can be expanded and contracted in the radial direction of the steel pipe. The method for shaping a steel pipe is characterized in that the steel pipe is squeezed while giving an orbital motion to the. In other words, to make it possible to change the roll position in the radial direction of the pipe and to change the drawing amount with the same roll, in order to make the radial position of the roll uniform, the pipe circle is set with the center of the pipe as a reference. It is rotated in the circumferential direction.

Further, the rolls have a function of causing a planetary motion by the rotation force, so that each roll squeezes the pipe while making a spiral motion with respect to the pipe. The deformation of the pipe in the circumferential direction rotates the roll in the circumferential direction, and the roll contact position becomes constant in the radial direction. Therefore, the drawing ratio becomes constant in the circumferential direction, and a pipe with high roundness is manufactured. be able to. Further, by expanding / contracting the position of the roll in the radial direction of the steel pipe, it is possible to form the pipe with an arbitrary pipe outer diameter and arbitrary drawing ratio.

In general pipe manufacturing, a coil is used and is bent in the width direction of a circular coil by means of rolls arranged in multiple stages and then welded. Therefore, the pipe that has been welded to be a closed pipe and the weld beads have been removed needs to be translated in the pipe axial direction without being twisted or rotated in the circumferential direction with respect to the pipe center. However, since the roll rotates and a force that rotates the pipe in the opposite direction of the roll revolution is generated, this becomes a force that rotates the pipe, so by adding a function to rotate in the roll revolution direction to cancel this. Since the pipe can be translated, it can be applied to the conventional manufacturing line.

[0009]

EXAMPLE As an example of the present invention, the apparatus shown in FIG. 3 was manufactured and drawn. The device includes a roll 2, a hydraulic motor 3 for rotating the roll 2, a roll support 4, a radial expansion / contraction device 5, and a rotation device 6 for assisting the revolution of the roll to prevent the pipe from rotating in the circumferential direction. Also comprises a rotary hydraulic valve device 7 capable of transmitting the roll rotation force.

Outer diameter D = 55.0 (mm) Wall thickness t = 2.0
(Mm) and outer diameter D = 20.0 (mm) wall thickness t = 1.0 (m
Figures 4 and 5 show the results of drawing the pipes with different drawing ratios and outer diameters with the same roll by changing the pipe m) in the radial direction of the rolls. In this embodiment, an increase in the amount of diaphragm,
Even if the outer diameter size is different, the roundness is not deteriorated and the roundness higher than that of the conventional opposed diaphragm device can be secured. Also, regarding the surface roughness, there is no increase in the surface roughness and it is at a level that is sufficiently satisfactory as a product.

[0011]

INDUSTRIAL APPLICABILITY As described above, the shaping method of the present invention is an industrial means as a means capable of forming a fixed shape by changing the size of a pipe without changing the rolls and without deteriorating the roundness and increasing the surface roughness. It can bring about a beneficial effect.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a conventional diaphragm device, and is a diagram of a two-roll system and a four-roll system.

FIG. 2 is a schematic diagram of deterioration of roundness when a pipe is squeezed by an amount of more than a proper squeezing amount by a conventional method.

FIG. 3 is an example of the present invention.

FIG. 4 is a relationship between the circularity and the draw ratio when draw forming is performed by the apparatus of FIG.

5 is a diagram showing the relationship between the surface roughness and the draw ratio when draw forming is performed by the apparatus of FIG.

[Explanation of symbols]

 1 Pipe 2 Roll 3 Hydraulic Motor 4 Roll Support 5 Radial Expansion / Reduction Device 6 Rotation Device 7 Hydraulic Valve Device

Claims (1)

[Claims] 1. A plurality of rolls are radially arranged with respect to a steel pipe, the roll itself has a rotation force, each roll can be expanded and contracted in a radial direction of the steel pipe, and the steel pipe is squeezed while giving a revolution motion to the rolls. A method for shaping a steel pipe, which is characterized in that