RU2270068C1 - Rolling mill for making seamless tubes - Google Patents

Abstract

FIELD: mills for rolling seamless tubes, namely steel seamless tubes.

SUBSTANCE: rolling mill includes predetermined number of rolls deforming outer periphery of tube or its blank and internal tool in the form of mandrel arranged coaxially relative to tube or its blank. Deformation range is created between rolls and said internal tool. Rolls and tool are suitable successively piercing tube blank and for elongating it tube. Rolls have in their both end zones at least one portion for gripping and transporting tube or its blank. Internal tool has in its axial end zone portion for piercing tube blank and cylindrical portion adjacent to said piercing portion and used for elongating tube.

EFFECT: possibility for performing combination process of piercing tube blank and elongating tube.

11 cl, 2 dwg

Description

Description

The invention relates to a rolling mill for the manufacture of seamless pipes, in particular steel pipes, containing a certain number of rolls deforming the outer periphery of the pipe or pipe billet, and an internal tool in the form of a mandrel located coaxially to the pipe or pipe billet, and an area is formed between the rollers and the internal tool deformations, and rolls and an internal tool, are suitable for sequentially flashing a pipe billet and extending the pipe.

The production of seamless steel pipes can take place on Kosovolkov rolling mills, the production process in which is divided into two stages. At the first stage, the steel ingot is fed into the rolling mill, and after it is captured by the rolls, the ingot is sewn into the hollow block with an internal tool in the form of a mandrel installed with the possibility of free rotation. At the second stage, elongation (extraction) occurs, i.e. the hollow block is rolled to the desired pipe.

Rolling is carried out, for example, in a three-roll transverse helical mill. In relation to the state of the art, reference should be made to DE-PS 259623 and DE-PS 259625. From the aforementioned state of the art, a conventional mowing rolling mill is known which works with conventional gauges of rolls and internal tools. However, it is impossible to make thin-walled sleeves on it. Therefore, the named rolling method is not competitive in comparison with modern methods of rolling pipes in a plant with a three-roll rolling mill.

If the manufacturing process is carried out in a known manner in two stages, then installations with a three-roll rolling mill for lengthening thin-walled workpieces in multi-roll transverse helical rolling mills require increased investment.

Therefore, for example, from DE 3717698 C2, flashing and pipe extension in a combined rolling process are known. At the first stage, the firmware is carried out, and here the axis of the roll and the stitched blank of the pipe is positioned relative to each other so that they form an angle. With subsequent elongation, the roll axis and the pipe axis are oriented parallel to each other.

The known methods further turned out that for a reliable and cost-effective production process very specific operational parameters had to be provided so that a combined process of flashing and lengthening a seamless pipe could be technologically and cost-effective.

In addition, it turned out that it was difficult to find the right technological conditions and the correct execution of the rolling mill, so that it was possible to realize the production of pipes in a wide range by manufacturing sleeves from thin-walled to thick-walled in the combined process of flashing and drawing.

In particular, this relates to the manufacture of seamless pipes in small batches.

Specific implementations of the mandrel and, in particular, the materials used for this are known from US 2197098.

The invention is based on the task of creating a rolling mill of the kind described above, with which it would be possible to reliably and cost-effectively carry out combined flashing and pipe extension.

This problem is solved, according to the invention, due to the fact that the rolls have in both axial end zones at least one segment made for gripping and transporting the pipe or pipe blank, and between the two roll sections provided in the axial end zones are cylindrical a segment made, while the internal tool has in the axial end zone a piercing segment for flashing the pipe billet, as well as a cylindrical segment adjacent to the piercing section, interacting with a cutter for lengthening the pipe, wherein the segments for gripping and transporting and the cylindrically made segment are arranged with respect to each other with the possibility of flashing and lengthening the pipe or pipe billet when the roll axis is parallel to the pipe axis or pipe billet.

Preferably, if at least one of the segments in the axial end zones of the rolls is conical. The angle of the cone of the segments is preferably 1-5 ^about . It may further be provided that in the axial end zone of the rolls in the direction of the other axial end zone, another cone-shaped section adjoins the cone-shaped section; the other cone-shaped segment may have a larger cone angle than the adjacent cone-shaped segment.

The pipe exit from the rolls is optimal if the axial ends of the rolls are made in the form of end sections radial in cross section.

With regard to the internal tool, it is recommended if a conically-shaped connecting segment adjoins the firmware section of the internal tool provided for firmware. The angle of the cone of the connecting segment is in this case mainly 2-15 ^about . It is further preferably provided that the conically-shaped connecting section consists of two sections having different angles of the cone. Particularly optimal deformation conditions arise when the cone angle of the second section of one connecting section is less than the cone angle of the first section of the connecting section.

An optimal view of the deformation region between the rolls and the inner tool is achieved when, according to one improvement, it is provided that the cone angle of one section of the connecting section of the inner tool is greater than the cone angle of the roll section.

Thanks to the proposed embodiment of the rolling mill and, in particular, the rolls and the internal tool used, it is possible to carry out the combined process of flashing and elongation in a very efficient manner, so that a technically perfect and reproducible production process is guaranteed, which, in addition, is cost-effective.

The invention is further explained using the description with reference to the drawings, which show:

- FIG. 1: schematically shows the position of the roll and the internal tool when flashing a tube stock;

- FIG. 2: elongation of the hollow block due to the interaction of the roll with the internal tool.

The drawings show one of three oblique rolls 2 that are evenly distributed along the periphery of the pipe 1 or workpiece 3 of the pipe 1, which, in cooperation with the internal tool 4, flash the workpiece 3 of the pipe 1 (Fig. 1) or extend (extend) then the prefabricated hollow block (Fig. . 2).

The rolls 2 are, therefore, rolls of a three-roll cross-helical rolling mill, which, in cooperation with the internal tool 4, carry out combined piercing and elongation of the workpiece 3 or pipe 1.

Combined firmware and extension by means of rolls 2 requires a specific calibration technique solution that would simultaneously meet both processes - firmware and extension. As shown below, the rolls 2 and the inner tool 4 are equipped with a special calibration, which provides rolling of a thin-walled hollow block and the subsequent manufacture of a thin-walled sleeve at the reverse stage.

The roller 2 and the inner tool 4 are thus specifically calibrated for deformation of said thin-walled hollow blocks.

In the schematic of FIG. 1, the billet 3 (block) is fed into the rolling mill and, after being captured by the rollers 2, it is rolled into a hollow block on an internal tool 4 mounted with free rotation.

To capture the block, the roll 2 has in its depicted in FIG. 1 left axial end zone 5 conically shaped section 7; the angle α _{1 of the} cone which is about 5 ^about , mainly 3-7 ^about .

Capturing a stitched block, i.e. hollow block, occurs located in the right axial end zone 6 of the roll 2, conically shaped segment 8 of the roll 2; the angle α _{2 of the} cone which is about 2 ^about , mainly 1-3 ^about .

To the segment 8 of the roll 2 in the direction of the axial end zone 5 of the roll 2 is adjacent another cone-shaped segment 12. The angle α _{1 of the} cone is larger and is about 7 ^about , mainly 5-9 ^about .

Between the conically shaped segments 12 and 7 of the roll 2 is a cylindrically made segment 13.

At both axial ends 14, 15 of the roll 2, there are end segments 16, 17 having a radial profile (radius R) in cross section to ensure optimal entry and exit of the pipe 1.

The inner tool 4 has a piercing section 10 in its axial end zone 9, with which the block can be formed into a hollow block in the usual way. The piercing segment 10 has a radial profile in longitudinal section (radius R).

After flashing, the reversing step is followed by an extension, for which the inner tool 4 has an elongated cylindrical section 11. In FIG. 2 shows the interaction of the roll 2 with a cylindrical segment 11, and it can be seen that the prefabricated pipe 1 (hollow block) is rolled into a finished seamless pipe 1.

The transition from the piercing section 10 of the inner tool 4 to the cylindrical section 11 is formed by the connecting section 18, 19. It is composed, as can be seen in FIG. 1, from two sections 18, 19, both sections 18, 19 of the connecting section being conical. The angles β ₁ and β _{2 of the} cones are indicated in FIG. 1, wherein it is seen that the angle β ₁ with neighboring tufting segment 10 connecting the segment 18 greater than the angle β ₂ with the adjacent cylindrical segment 11 of the connecting segment 19. The values of β ₁ to about 13 ^o, preferably ^about 11-15, and β ₂ to approximately 4 ^about , mainly 2-6 ^about .

As already mentioned, in the manufacture of seamless pipe 1, first in the first stage, i.e. when flashing, the block (billet 3) is gripped by rolls 2 and rolled out on the internal tool 4 installed with the possibility of free rotation into a hollow block. At the input, the rolled product does not have contact with the end segment 16. The segment 7 with its cone angle α ₁ is made so that, on the one hand, the rolling product is gripped, and on the other hand, the axial resistance of the mandrel is overcome.

In addition, in the second stage of production, i.e. when lengthening, unnecessary loading or twisting of the rolled product due to expansion or triangulation at the exit of the rolling mill should be prevented.

The cylindrically made section 13 runs parallel to the rolling axis. The other segment 12 and its cone angle α _{2 are} designed so that at the first stage (firmware), an increase in diameter can occur while reducing the wall thickness of the rolled product, due to which the triangulation of the ends of thin-walled hollow blocks caused by the process is noticeably suppressed or reduced.

Section 8 of the roll 2 is made conical. At the first stage (firmware), this segment in combination with the internal tool 4 serves to ensure uniformity of the wall thickness of the hollow block, and at the second stage (extension), it engages the rolled product. The angle α _{3 of the} cone is chosen so that both of these conditions are met.

The inner tool 4 consists of these three segments. The flashing section 10 serves to flush the block and to reduce the wall thickness for the most part. It is made radial or curved. The connecting segments 18, 19 are made conical, and on the connecting segment 18 there is a residual decrease in wall thickness to obtain a nominal wall, as well as a targeted increase in the diameter of the hollow block. The angle β _1, respectively, is greater than the angle α ₂ . On the connecting section 19, the wall thickness of the pipe 1 becomes uniform.

Elongation occurs in the opposite direction of the rolling direction.

After the first stage (firmware), the rolls 2 are moved to the working position for the second stage (extension). At the same time, the inner tool 4 is moved to the desired axial position and lubricated. During rolling, the inner tool 4 under control is moved towards the rolling direction.

For extension, the rolled product is captured in the area of the segment 8 of the roll 2. The angle α _{3 is} chosen here so that the gripping condition is met. The task of another segment 12 of the roll 2 is to reduce the wall thickness of the rolled product to a nominal value in cooperation with the internal tool 4. This segment is performed as short as possible to avoid a strong increase in the diameter of the rolled product.

A cylindrically made segment 13 of the roll 2 runs parallel to the mandrel to achieve uniform wall thickness. Adjacent to the segment 13, the segment 7 of the roll 2 has an angle α _{1 of the} cone. The deformation region in this zone should increase rapidly in the direction of exit of the rolled product in order to give it a round shape and to avoid twisting.

Since capture occurs on this segment at the first stage (firmware), the angle α _{1 of the} cone cannot be chosen too large. For this reason, to the segment 7 adjoins the end segment 16 of the roll 2, which is made radial and quickly releases the rolled product.

When rolling thin-walled sleeves in the area of their ends, a thicker wall should be obtained than in the middle part in order to minimize the triangulation of the ends caused by the production process. To do this, in the zone of ends of the rolled product, the deformation region after the start of rolling is reduced to the nominal, and by the end of the rolling increase from the nominal area (the so-called "Quick Closing - Quick Lifting"; DE 19724233 A1).

To optimize the rolling process, it is provided that quick adjustment of the tilt angle (the angle between the roll axis and the rolling axis) is carried out between the first (firmware) and second (extension) stages in order to expand the operating range. Due to this, it is possible to produce even more thin-walled sleeves.

Thanks to the proposed implementation, a combined piercing-rolling mill is capable of producing not only relatively thick-walled pipes, but also realizing the same production range as modern tube rolling units with a three-roll rolling mill. The advantage achieved by this is that a reduction in investment is possible compared to modern three-roll mills. In addition, it is possible at lower annual capacity to reduce the cost of production.

List of Reference Items

1 - pipe

2 - roll

3 - pipe billet

4 - internal tool

5 - axial end zone of the roll

6 - axial end zone of the roll

7 - roll section

8 - roll section

9 - axial end zone of the inner tool

10 - piercing piece of the internal tool

11 - cylindrical segment

12 - another segment of the roll

13 - cylindrical roll section

14 - axial end of the roll

15 - axial end of the roll

16 - end segment of the roll

17 - end segment of the roll

18 - section of the connecting piece of the inner tool

19 - section of the connecting piece of the inner tool

α ₁ - cone angle

α ₂ - cone angle

α ₃ - cone angle

β ₁ - cone angle

β ₂ - cone angle

R is the radius

Claims (11)

1. Rolling mill for the manufacture of seamless pipes (1), in particular steel pipes, containing a certain number of rolls (2), deforming the outer periphery of the pipe (1) or workpiece (3) of the pipe (1), and an internal tool (4) in the form a mandrel located coaxially to the pipe (1) or the workpiece (3) of the pipe (1), and between the rolls (2) and the internal tool (4), a deformation region and the rolls (2) are formed and the internal tool (4) are suitable for sequential flashing of the workpiece ( 3) of the tube (1) and the extension tube (1), characterized in that the rollers (2) have in both axial end zones (5, 6), at least one segment (7, 8) made to capture and transport pipe (1) or pipe billet (3) (1) between both axial end zones (5, 6) ) by segments (7, 8) of the rolls (2), a cylindrically made segment (13) is located, and the internal tool (4) has a piercing section (10) in the axial end zone (9) for piercing the billet (3) of the pipe (1), and also a cylindrical segment (11) adjacent to the piercing segment (10), interacting with a cylindrically made segment (13) to extend the pipe (1), and the segments (7, 8) for capture and transportation, and a cylindrically made segment (13) are located relative to each other with the possibility of flashing and elongation of the pipe (1) or billet (3) of the pipe (1) with the roll axis (2) parallel to the pipe axis (1) or billets (3) pipes (1). 2. The mill according to claim 1, characterized in that at least one of the segments (7, 8) in the axial end zones (5, 6) of the rolls (2) is made conical. 3. The mill according to claim 2, characterized in that the angle (α ₁ , α ₂ ) of the cone of the segments (7.8) is 1-5 ^about . 4. The mill according to claim 2 or 3, characterized in that in the axial end zone (6) of the rolls (2) in the direction of the other axial end zone (5), another cone-shaped section (12) adjoins the cone-shaped section (8). 5. Mill according to claim 4, characterized in that the other conically-shaped section (12) has a larger cone angle (α ₂ ) than the adjacent conically-shaped section (8). 6. Mill according to one of claims 1 to 3, characterized in that the axial ends (14, 15) of the rolls (2) are made in the form of end sections radial in cross section (16, 17). 7. The mill according to one of claims 1 to 3, characterized in that a conically-shaped connecting segment (18, 19) is adjacent to the firmware section (10) intended for firmware of the internal tool (4). 8. The mill according to claim 7, characterized in that the angle (β ₁ , β ₂ ) of the cone of the connecting section (18, 19) is 2-15 ^about . 9. The mill according to claim 7, characterized in that the conically-shaped connecting section (18, 19) consists of two sections having different angles (β ₁ , β ₂ ) of the cone. 10. The mill according to claim 9, characterized in that the second angle (β ₂ ) of the cone of the section (19) of the connecting section is less than the first angle (β ₁ ) of the cone of the section (18) of the connecting section. 11. The mill according to claim 10, characterized in that the angle (β ₁ ) of the cone of the connecting segment (18) of the inner tool (4) is greater than the angle (β ₂ ) of the cone of another segment (12) of the rolls (2).

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