JPH0377005B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides, in order of use, a heating device, an inclined roll punching machine, a plug rolling machine, a diameter expanding rolling machine,
and a shaping rolling mill directly following the diameter expanding rolling mill;
The present invention relates to a rolling equipment that includes a cooling bed and that manufactures thin-walled seamless steel pipes from solid bars of a specific length.

The diameter expanding rolling mill used in the present invention is a so-called inclined rolling mill in which the axes of two or more rolls are arranged at an angle with respect to the axis of the rolled steel material. lowest against
The rolls are arranged at an opening angle of 2° to a maximum of 35°, especially about 15°, and each roll has a contour line consisting of a conical entry part and a rotational hyperboloid part, and each roll is supported on both sides by roll stands. and all rolls,
The roll gap is made to work together with a common fixed core bar provided between the rolls, and the roll gap is tapered in the rolling direction by the rolls and the core bar.

This type of rolling equipment for producing thin-walled seamless steel pipes is described in Tetsu to Hagane (1933), pages 693-695. In this publication, a Pilger rolling mill is specifically proposed as a rolling mill, and it is confirmed that the problem of manufacturing thin-walled seamless steel pipes with the above-mentioned inclined rolling mill according to the present invention is still unsolved. Others, since and despite this publication,
The rolling equipment based on this proposal was never actually used.

In recent years, demand for thin-walled tubes with a diameter of about 350 mm or more has been increasing, for example, in the energy industry. The manufacture of this type of tube is not only quite difficult due to its relatively thin wall thickness, but also requires considerable expenditure on equipment, such as the Pilger rolling mill mentioned above in Iron and Steel. Investments were getting expensive.

Additionally, equipment using the Pilger rolling mill requires an intermediate heating process for rolled steel, and the work cycle of the equipment depends on this process, making this type of rolling equipment less adaptable to changes in demand. It was hot.

Therefore, it is technically valid to combine the production of seamless steel pipes with the subsequent pipe expansion process, and this proposal simultaneously has the following multiple objectives.

1. Only one heating process is required to reach the finish.

2 Smooth out the thickness in hot water.

3. Stretch the thickness of the hollow body in stages.

4. Achieve dimensional accuracy of diameter.

That is, an object of the present invention is to simplify the production of thin-walled steel pipes in terms of equipment and to improve the technology.

This purpose consists of, in order of use, a heating device, an inclined roll punching machine, a plug rolling mill, a diameter expanding mill, a shaping mill directly following said diameter expanding mill, and a cooling bed. The machine is an inclined rolling mill of a type in which the axes of two or more rolls are arranged at an angle with respect to the axis of the rolled steel material, and the axis projection of each roll is at an opening angle of at least 2 degrees to a maximum of 35 degrees with respect to the axis of the rolled steel material. The outline of each roll is composed of a conical entry part and a rotational hyperboloid part, each roll is supported on both sides by roll stands, and all rolls are connected to a common fixed core between the rolls. By working together with gold, the rolls and core metal form a roll gap that tapers in the rolling direction, and the rolling equipment manufactures thin seamless steel pipes from solid bars of a specific length. resolved.

Here, although it is known that the wall thickness of steel pipes normally produced by a plug rolling mill is not sufficiently uniform, it has been found that the combination according to the present proposal described above is technically advantageous.

In addition, plug rolling mills as vertical rolling mills operate faster than, for example, Pilger mills, and do not require an intermediate heating process up to the shaping mill, which means that the cost of high-temperature energy is rapidly increasing. It is especially important at present.

Additionally, an inclined rolling mill for stretching can be additionally provided in front of the plug rolling mill, and a hollow body can be formed from a solid bar using, for example, two inclined rolling mills installed in front and behind each other, as is well known. However, the hollow body may be used as a blank for a plug rolling mill according to the present proposal, and then the diameter may be expanded.

The steel pipe manufactured by the plug rolling mill is sent to the diameter expanding mill according to the present invention described above and expanded to a desired diameter. The diameter expanding mill determines the diameter of the finished tube, and can expand a diameter of 350 mm to 500 mm or more, for example.

A special configuration of the roll and core shape is particularly advantageous and is the subject of a separate application of the same year. According to this, various diameters of the tube can be determined by changing the length of the core metal, making it easier to rearrange the equipment and the necessary equipment when changing dimensions.

According to the experimental investigation of the present proposal, diameter enlargement can be of considerable help in homogenizing the wall thickness, especially when applying hole-type calibers such as those proposed elsewhere, and the latter stage of the plug mill or diameter enlargement mill. There is no need to provide a special inclined roll (reeler), and the equipment becomes cheaper.

This eliminates the otherwise necessary intermediate heating step, which particularly reduces heating costs. Rather, according to the invention, the steel tube is sent directly from the diameter-expanding mill to the shaping mill, where it is rounded and its diameter is reduced by a few mm.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

Here, the rolling equipment shown in FIG. 1 includes a rotary furnace 1, an inclined roll punching machine 2, a plug rolling mill 3,
It consists of a diameter expanding mill 4, a shaping mill 5, and a cooling bed 6.

First, a solid billet is put into the rotary furnace 1 in the direction of arrow 7, heated to about 1250 degrees, and taken out in the direction of arrow 8.

The heated billet 9 is descaled and centered, and then fed to an inclined roll punching machine 2 having a core bar 10 fixed within a support. This results in a hollow body that is still warm enough to undergo extensive hot forming.

If the hollow body 11 is relatively thin, it is immediately sent to the plug mill 3.

The plug mill 3 consists of a pair of rolls 12 cooperating with a core 14 supported in supports 13 . The hollow body 11 is fitted onto the core rod 15, the roll 12 is opened, and the hollow body is pushed back by the drive roll 16.

In general, the plug rolling mill 3 consists of just one set of rolls, which are passed through several times, in particular twice (two passes),
Form a hollow body. Therefore, a narrower roll spacing and/or a larger core diameter is selected for each pass.

After the final plug pass, the hollow body 11 is returned from the rolling mill and fed, preferably in cross feed, to the diameter expanding mill 4.

The diameter expansion rolling mill 4 includes an inclined roll 17 and a diameter expansion core bar 1 held by a support (not shown).
It consists of 8.

This device is shown in an enlarged view in FIG. It can be seen from the figure that the roll 17 is in an inclined position with respect to a plane passing through the tube axis 19, that is, the illustrated plane. The upper roll is downward to the right with respect to the illustrated plane, and the lower roll is downward to the left. The opening angle formed by the tube axis 19 and the projection of the roll axes 20 and 21 on the illustrated plane is, respectively,
The angle is between 2° and 35°.

FIG. 3 shows the outline of the roll 17. The contour line consists of a conical section 22 and a hyperboloid of revolution section 17.

As a result of this contour and inclined position, roll 17
The spiral winding conforms to the shape of the hollow conical part 23 without any difficulty, and its axis 19 coincides with the conical part 1 of the diameter expanding core metal.
It coincides with the axis of 8.

The hollow body leaves the above-mentioned diameter expanding mill 4 as a seamless finished tube with a uniform wall thickness, is sent to a shaping mill 5 at about 900°C for diameter correction, and is cooled to room temperature on a cooling bed 6. .

After cooling, normal conditioning and inspection work is performed according to the specifications.

In addition, in FIG. 1, it is also possible to supplement a drawing inclined rolling mill 24 between the punching machine 2 and the plug rolling mill 3. In this case, at least this drawing rolling mill 24 can connect the plug rolling mill 3. A hollow body is created that is thin enough for the roll.

[Brief explanation of drawings]

FIG. 1 shows the technical arrangement of equipment in a rolling mill. FIG. 2 is a longitudinal sectional view of the diameter expanding mill in the tube axis plane. FIG. 3 is a longitudinal cross-sectional view of the enlarged diameter roll in the plane of the roll axis. 1... Rotary furnace, 2... Inclined roll type drilling machine,
3... Plug rolling mill, 4... Diameter expansion rolling mill, 5...
...Shaping rolling mill, 6...Cooling bed, 9...Billet,
11...Hollow body, 12...Pair of rolls, 14...Core bar, 24...Stretch rolling mill.

Claims (1)

[Claims] 1 Listed in order of use, it consists of a heating device, an inclined roll punching machine, a plug rolling mill, a diameter expanding mill, a shaping mill directly following the diameter expanding mill, and a cooling bed, and the diameter expanding mill is An inclined rolling mill of a type in which the axes of two or more rolls are arranged at an angle with respect to the axis of the rolled steel material, and the axis projection of each roll is arranged at an opening angle of at least 2° to maximum 35° with respect to the axis of the rolled steel material. , and the contour line of each roll is composed of a conical entry part and a rotational hyperboloid part, and each roll is supported by roll stands on both sides, and all rolls are connected to a common fixed core metal provided between the rolls. A rolling equipment that manufactures thin-walled seamless steel pipes from solid bars of a specific length, and has a configuration in which rolls and core metals form a roll gap that tapers in the rolling direction.