JP2924593B2 - Manufacturing method of seamless steel pipe with threaded part - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a seamless steel pipe having a threaded portion for an oil well which requires threading at the pipe end by a Mannesmann plug mill method.

[0002]

2. Description of the Related Art A seamless steel pipe is manufactured by a Mannesmann plug mill method by forming a hole in the center of a round steel slab heated using a piercer to form a base tube. If necessary, the base tube can be thinned by an elongator. After expanding the diameter, it is stretched and rolled by a plug mill, further passed through a reeler and a sizer, subjected to polishing, shape correction and sizing, and cooled to room temperature to obtain a seamless steel pipe having a predetermined size specification.

[0003] Since seamless steel pipes manufactured by the Mannesmann plug mill method are manufactured with priority given to guaranteeing the steel pipe dimensions at the time of rolling, in order to obtain a seamless steel pipe with an upset for an oil country tubular good, the steel pipe dimensions (outside (Diameter, inner diameter, wall thickness) and dimensions required for threading do not match, so after rolling, upset processing such as expansion, contraction, and thickening of the threaded part is performed separately, and the threaded part required for joint processing The dimensions are secured.

[0004]

In order to perform the upsetting of the seamless steel pipe, not only an upsetter but also a pipe end heating furnace, a tool cooling device, a lubricant applying device, a handling device and the like are required. Since the upset processing requires a considerable cost, the seamless steel pipe becomes expensive, and therefore there is a strong demand for the development of a method of manufacturing a seamless steel pipe with a threaded portion that can omit the upset processing.

An object of the present invention is to provide a method for manufacturing a seamless steel pipe with a threaded portion, which can omit upsetting such as expansion, contraction, and thickening of the threaded portion after rolling.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted various tests and researches to achieve the above object, and as a result, previously set a thickness variation pattern in the pipe axis direction of a seamless steel pipe having a threaded portion, By adjusting the roll gap of the plug mill based on the thickness variation pattern and performing elongation rolling, it was confirmed that the thickness of the threaded portion could be controlled to a predetermined value, and the present invention was reached.

That is, a first invention of the present application is a method of manufacturing a seamless steel pipe by the Mannesmann plug mill method, wherein a thickness variation pattern is set in advance in the pipe axis direction of the seamless steel pipe with a threaded portion, plug mill according to the change pattern, drawing and rolling by adjusting the roll gap of Leela, Migakukan, and shape correction, after controlling the thickness of the threaded portion to a predetermined value, the roll gap of Sa Isa for internal upset adjustment without a threaded portion with a seamless steel manufacturing method, characterized by subjecting the sizing.

A second invention of the present application is a method of manufacturing a seamless steel pipe by the Mannesmann plug mill method, wherein a thickness variation pattern is set in advance in the pipe axis direction of the seamless steel pipe with a threaded portion, plug mill based on the thickness variation pattern, drawing and rolling by adjusting the roll gap of Leela, Migakukan, and shape correction, after controlling the thickness of the threaded portion to a predetermined value, if the external upset and the inner and outer upset
Is a threaded portion with a seamless steel manufacturing method, characterized by subjecting the grass customizing a varying wall thickness of the threaded portion to adjust the roll gap of the service organizer.

[0009]

According to the present invention, a thickness variation pattern in the pipe axis direction of a seamless steel pipe having a threaded portion is set in advance , and a roll gap of a plug mill and a reeler is adjusted based on the thickness variation pattern, and elongation rolling is performed . Migakukan, and shape correction, after controlling the thickness of the threaded portion to a predetermined value without the case of the inner upset adjusting the roll gap of the service organizer, because performing Size Lee <br/> managing, plug mill, Outer circumference of pipe end with reeler
The thick threaded part formed on the surface overhangs the inner peripheral surface,
The thickness of the threaded portion required for joint processing can be secured, and upsetting such as pipe expansion, contraction, and thickening of the threaded portion after rolling can be omitted.

In a method of manufacturing a seamless steel pipe by the Mannesmann plug mill method, a thickness variation pattern is set in advance in a pipe axis direction of a seamless steel pipe with a threaded portion , and a plug mill is set based on the thickness variation pattern . Leela <br/> to adjust the roll gap stretching rolling, Migakukan, after to shape correction <br/>, to control the thickness of the threaded portion to a predetermined value, external upset, in the case of internal and external upset, Sa Do not change the thickness of the threaded part by adjusting the roll gap
By applying grass customizing, can be ensured thickness dimension of the threaded portions necessary for joint processing, pipe expansion threaded portion after rolling, the reduced pipe can be omitted upset processing such as thickening.

[0011]

【Example】

Embodiment 1 Hereinafter, details of the present invention will be described with reference to FIGS. 1 to 3 showing an embodiment. FIG. 1 is a schematic side view showing an embodiment of a rolling method in a plug mill according to the present invention, FIG. 2 is a schematic cross-sectional view of a seamless steel pipe having a thickened pipe end threaded portion, and FIG. 3 is a pipe shaft in a plug mill. It is a schematic diagram which shows an example of the thickness variation pattern of a direction. In FIG. 1, 1 is a plug mill, 2 is a reeler, 3 is a sizer, and 4 is a cooling stand. The base tube 5 perforated by a piercer (not shown) and expanded in diameter by an elongator is repeatedly stretched and rolled by a plug mill 1 composed of a pair of caliber rolls 6a and 6b and a plug 8 supported by a mandrel 7. The tube 9 stretched and rolled by the plug mill 1 is subsequently passed through a pair of cylindrical rolls 10.
a, 10b and a plug 12 attached to the tip of a mandrel 11, etc., and sent to a reeler 2 and moved in a spiral by a pair of columnar rolls 10a, 10b and penetrated into a core hole and a circle. The inner and outer peripheral surface properties are enhanced by the columnar rolls 10a and 10b.

The tube 13 that has passed through the reeler 2 is introduced into a sizer 3 in which a pair of caliber rolls 14a and 14b are alternately arranged at 90 ° positions, and the outer diameter and the wall thickness are finished to predetermined dimensions. Cooled to the normal temperature by the cooling stand 4, it becomes a seamless steel pipe. Reference numeral 15 denotes a control unit for adjusting the roll gap of the plug mill 1, the reeler 2 and the sizer 3, and as shown in FIG. 2, a threading unit 16 is provided on the top and bottom of the pipe via a console 17 in advance. plug mill shown in FIG. 3, Lee
Tube axis direction of the thickness variation pattern of La is input set, the caliber rolls 6a of plug mill 1, reduction of 6b device 1
8. The opening / closing device 19 of the cylindrical rolls 10a and 10b of the reeler 2 is operated to control the roll gap. The figure
In the case of inner upset as shown in Fig. 2, as shown in Fig.
Open the roll gap of plug mill 1 and reeler 2
To increase the thickness of the threaded portion at the pipe end to the outer circumference of the pipe.
After setting the roll gap of sizer 3 to
Constant adjustment without adjustment at the top and bottom
By sizing with the tool opening,
Rag mill 1 and reeler 2 increase the wall thickness on the outer circumference of the pipe.
As shown in Fig. 2, a threaded portion 16
Is obtained.

Further, the control unit 15, when the outer upset and the inner and outer upsetting, plug mill 1 in service organizer 3, Li
Elongation rolling in over La 2, Migakukan, to apply grass customizing a <br/> varying the thickness of the threaded portion 16 of the top portion and the bottom portion of the tube 9, which is shape correction, Sa Isa 3 a pair of caliber rolls 14a arranged alternately shifted by 90 ° position, the roll gap of the 14b, the outer upsetting or out upset
Corresponding calculated, the caliber roll 14a of Sa Isa 3, 14b
Operating the switchgear 20, the outer upsetting or out Apuse
Tsu is configured to control the roll gap was calculated corresponding to and.

With the above-described configuration, the control unit 15 is configured to input and set in advance via the console 17 FIG.
The plug mill 1 has a roll gap variation pattern calculated based on the wall thickness variation pattern in the pipe axis direction shown in
The caliber rolls 6a and 6b, the rolling device 18 and the reeler 2
Since the opening / closing device 19 for the cylindrical rolls 10a and 10b is operated in the above, the thickness of the threaded portion is ensured at the top and bottom of the tube 9 on the sizer 3 entrance side. The control unit 15
Is plug mill 1 in service organizer 3, extending <br/> Shin rolling in Leela 2, Migakukan, such that varying the thickness of the threaded portion 16 of the top portion and the bottom portion of the pipe 9 which is shaped modified grass Lee <br/> to performing managing, in situ Gosa Isa 3 of the upset tube 9
The top portion and the adjustment of the roll gap at the bottom portion is not performed, if the external upset and the inner and outer upsetting, Size Lee <br/> The third 90 ° a pair of which are arranged alternately position by shifting caliber rolls 14a, 14b It calculates the roll gap of the difference Isa
Since the roll gap is controlled by operating the opening / closing device 20 of the caliber rolls 14a and 14b, a threaded portion 16 having a predetermined thickness is formed at the top and bottom of the seamless steel pipe on the exit side of the sizer 3. You. Therefore, according to the method of the present invention, it is not necessary to perform upsetting such as expansion, contraction, and thickening of the threaded portion on the seamless steel pipe after rolling, and the upsetting can be omitted.

Example 2 Outer diameter 323.9 mm, wall thickness 12.7 mm, length 1200
In order to form a threaded portion 2m with a correction amount of 0.5mm, 1.0mm and 1.5mm at the bottom of the tube using a plug mill using 80 0mm tubes, the thickness change pattern shown in the uppermost part of FIG. The roll gap control of the plug mill was performed by inputting the settings, and the results were measured using a performance chart of the pipe end wall thickness change.
FIG. 4 shows the results. As shown in FIG. 4, the thickness of the threaded portion at a predetermined correction amount was ensured, and the upset process after rolling could be omitted.

[0016]

As described above, according to the method of the present invention, a seamless steel pipe with a threaded portion can be manufactured, so that upsetting such as expansion, contraction, and thickening of the threaded portion after rolling is omitted. Accordingly, a seamless steel pipe with thread can be manufactured at a low cost.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an embodiment of a rolling method in a plug mill according to the present invention.

FIG. 2 is a schematic cross-sectional view of a seamless steel pipe in which a pipe end threaded portion is thickened.

FIG. 3 is a schematic diagram showing an example of a wall thickness variation pattern in a tube axis direction in a plug mill.

FIG. 4 is a performance chart showing a relationship between a wall thickness change pattern, a distance from a bottom end, and a pipe end wall thickness change in Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plug mill 2 Reeler 3 Sizer 4 Cooling stand 5 Raw tube 6a, 6b, 14a, 14b Caliber roll 7, 11 Mandrel 8, 12 Plug 9, 13 Tube 10a, 10b Cylindrical roll 15 Control part 16 Screw processing part 17 Operation table 18 Roll-down device 19, 20 Switchgear

Claims (2)

(57) [Claims] In a method of manufacturing a seamless steel pipe by a Mannesmann plug mill method, a thickness variation pattern is set in advance in a pipe axis direction of a seamless steel pipe with a threaded portion , and a plug mill is formed based on the thickness variation pattern . elongation rolling by adjusting the roll gap of Leela, Migakukan, and shape correction, after controlling the thickness of the threaded portion to a predetermined value, in the case of internal upset without adjusting the roll gap of the service organizer,
Method for producing a threaded portion with a seamless steel pipe, characterized in that applying the sizing. 2. A method for manufacturing a seamless steel pipe by a Mannesmann plug mill method, wherein a thickness variation pattern is set in advance in a pipe axis direction of a seamless steel pipe with a threaded portion , and a plug mill is formed based on the thickness variation pattern . adjust the roll gap elongation rolling of Leela, Migakukan, after to shape correction, to control the thickness of the threaded portion to a predetermined value, external upset
And manufacture of threaded portion with a seamless steel pipe, characterized in that applying the grass Lee <br/> managing a varying wall thickness of the threaded portion to adjust the roll gap of Sa Isa when the inner and outer upset Method.