JPS5970409A - Rolling facility manufacturing thin seamless pipe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises, in the order of use, a heating device, a drilling machine, a drawing machine, a diameter expanding mill, and a cooling section, and is a rolling mill for producing thin-walled seamless steel pipes from a solid bar of a specific length. Regarding equipment.

Two or more diameter expansion mills are installed on the axial plane of the rolled steel material □
This is a so-called inclined rolling mill in which the axes of the upper rolls are arranged at an angle, and the axis projection of each roll relative to the plane is at a minimum of 2 degrees to a maximum of 35 degrees, particularly 15 degrees, with respect to the axis of the material to be rolled.
Each roll is supported on roll stands on both sides.

All the rolls cooperate with a common fixed mandrel provided between the rolls, and the rolls and the mandrel form a tapered roll gap in the rolling direction.

This type of rolling equipment was introduced in “Tetsu to Hagane J (1933) No.
It is described on pages 3-695. In this publication, a pilger rolling mill is specifically proposed as a drawing machine, and it is confirmed that the problem of producing thin-walled finished tubes with an inclined rolling mill is still unsolved. Additionally, it can be confirmed that since and despite this publication, rolling plants according to this proposal have never been used in practice with an enlarged diameter mill.

Thin-walled tubes with a diameter of about 350 m or more are increasingly in demand, for example in the energy industry. Seamless tubing is also required. The production of tubes of this type is not only difficult due to the relatively thin wall thickness, but also requires considerable expenditure in terms of equipment for the pilger mill.

Equipment of this type, for example pilger hot rolling mills in this size range, generally has high capital costs. Because the rolled steel must be cooled and the operating cycle of the equipment depends on this, this type of rolling mill is less adaptable to changes in demand.

Therefore, it is technically valid to combine the production of seamless steel pipes with the subsequent pipe expansion process.

However, this proposal simultaneously raises several contradictory objectives.

1. As much as possible, the heating process up to the finished pipe can be completed only once.

z　Thickness should be smoothed out by hot heating.

3. Gradating the thickness of the hollow body or stretching it in stages.

4. Dimensional accuracy of diameter.

The object of the invention is to simplify and technically improve the production of thin-walled steel pipes in terms of equipment.

This object is achieved by selecting and partially combining known devices for rolling mills used in the order listed in the similar concept.

It has been found that plug rolling mills are technically advantageous in the proposed combination, even though it is known that the wall thickness of the steel tubes produced in this way is not sufficiently uniform. However, the elongation of the hollow body wall thickness, which can typically be achieved in 92 passes using a plug mill, is sufficient to feed the tube into a diameter expansion mill.

As a vertical rolling mill, a plug mill operates faster than, for example, a pilger-incline mill, so that no intermediate heating steps are required up to the shaping mill. This is especially important now that the cost of high temperature energy is rapidly increasing.

Supplementarily, an inclined rolling mill for elongation can be provided before the plug rolling mill, and a hollow body is formed from a solid bar using, for example, two inclined rolling mills arranged in front and behind each other, as is well known. The body is made into a blank for a Sibrag rolling mill according to this proposal, and its ridge diameter is expanded.

The steel pipe produced by the plug rolling mill is sent to the diameter expansion mill, where it is expanded to the desired diameter. In more detail, the described apparatus is used as a diameter enlarging mill. The rolls of the device are provided with a hole-shaped caliber relative to the conical core so as to create a tapered roll gap in the rolling direction. The diameter of the finished tube is determined by the 5-diameter expansion mill. The wall thickness of the finished tube is already prepared in each expanding plug mill. For example, a diameter of 350 mm can be expanded to a diameter of 500 wL or more.

It is particularly advantageous to feature the shape of the roll and core metal,
This point is the subject of a separate application of the same year. According to this, the roll has the shape of a hyperboloid of rotation, and the core metal is mainly in the shape of a truncated cone. By changing the length of the mandrel, various diameters of the tube can be determined, making it easier to rearrange the equipment and the necessary equipment when changing dimensions.

From the experimental investigation of the present proposal, it has been shown that diameter enlargement is of considerable help in homogenizing the wall thickness, especially when applying hole-shaped calibers as proposed elsewhere, and that special There is no need to provide an inclined roll (reel), and the equipment becomes cheaper.

This eliminates the otherwise necessary intermediate heating step, which particularly reduces heating costs.

Rather, the steel tube according to the invention is sent directly from the diameter expansion mill to a 61-shape rolling mill where it is rounded and reduced to a diameter of several nanometers.
be offended.

The present invention will be explained in detail by means of illustrated embodiments.

In FIG. 1, the rolling equipment includes a rotary furnace 1, a punching machine 2, a plug mill 3, a diameter expanding mill 4, a shaping mill 5, and a cooling section 6.
Consists of. The solid billet is placed in the rotary furnace 1 in the direction of arrow 7, heated to about 1250' and removed from the furnace in the direction of arrow 8. The heated billet 9 is descaled and centered and fed to an inclined rolling mill 2 having a mandrel 10 fixed in a support. A hollow body is obtained that is still warm enough to undergo extensive thermal deformation. If the hollow body 11 is relatively thin 2, it is immediately sent to the plug rolling mill 3.

The plug rolling mill 3 includes a core 1 supported within a support 13.
4 and co-operating pair rolls 12. The hollow body 11 is fitted onto the mandrel rod 15, the roll 12 is opened, and the hollow body is pushed back by the drive roll 16. Generally, plug rolling mill 3 is just 1
A set of rolls is made up of several passes, in particular two passes as described above (two passes). Two pairs of rolls 12 of this kind can also be arranged side by side.

To form the hollow body, a narrower roll spacing and/or a larger mandrel diameter is selected for each pass.

After the final plug pass, the hollow bodies 11 are returned from the mill and fed to the opening mill 4, preferably with a cross feed. Hiraki Mill 4
consists of an inclined roll 17 and a diameter-enlarging mandrel 18 held by a support, also not shown. This device is shown in an enlarged view in FIG.

It can be seen that the roll □ is in an inclined position with respect to the plane passing through the tube axis 19, that is, the plane shown. The upper roll is located at the lower right of the plane of illustration, and the lower roll is located at the lower left. The opening angle formed by the tube axis 19 and the projection of the roll axes 20, 21 relative to the plane of illustration is in each case between 2° and 35°. 6th
The figure shows the contour of the roll, which consists of a conical section 22 and a hyperboloid section 17.As a result of this contour and the inclined position, the spiral winding of the roll is located within the cone of the hollow body. The axis 19 thereof coincides with the axis of the conical part 18 of the diameter-enlarging mandrel.

The hollow body leaves the diameter expansion mill as a seamless finished tube with uniform wall thickness, is sent to a shaping mill 5 at about 900° C. for diameter correction, and is cooled to room temperature in a cold section 6. After cooling, normal conditioning and inspection operations are performed according to the specifications.

In FIG. 1, if a drawing inclined rolling mill 24 is added between the punching machine 2 and the plug rolling mill 3, it becomes another rolling equipment.

At the latest with this elongation mill 24, a hollow body is produced which is sufficiently thin for a plug roll.

[Brief explanation of the drawing]

Figure 1 shows the technical layout of equipment in a rolling mill. FIG. 2 is a vertical cross-sectional view of the diameter expanding mill in the plane of the tube axis. FIG. 3 is a longitudinal cross-sectional view of the diameter-enlarging roll in the roll axis plane. 9- 1...Rotary furnace, 2...Drilling machine, 3...Plug rolling machine, 4...
・Diameter expansion mill, 5... Shape rolling mill, 6.
...Cooling section, 9...Billet, 11...
...Hollow body, 12...Anti-roll,
14... Core metal, Sae... Stretching rolling machine.

Claims (1)

[Scope of Claims] 1.' Listed in the order of use, a heating device, a punching machine, a stretching machine, a diameter expanding mill, and a cooling section are used to form a forming machine and a diameter expanding mill,
An inclined rolling mill of the type in which two or more row shafts are arranged at an angle with respect to the axial plane of the rolled steel material, sb, where the projection of the roll axis on the plane is at least 2° to at most 35° with respect to the rolling axis.
°, in particular with an opening angle of less than 15°, each roll is supported on roll stands on both sides, all rolls cooperate with a common fixed mandrel placed between the rolls, and rolling is carried out by the rolls and mandrel. forming a tapered roll gap in the direction,
In a rolling facility for manufacturing thin-walled seamless steel pipes from solid bars of a specific length, a) the drawing device is optionally connected to an inclined rolling mill 24 and/or
or unavoidably comprising a plug rolling mill 3; b) Technically speaking, rolling equipment is characterized in that it is directly connected to the diameter expanding mill 4 and a shaping rolling mill 5 (vertical rolling mill) is provided in front of the cooling section 6. .