DE2755058A1 - METHOD OF MANUFACTURING SEAMLESS TUBES ON A BUTTON - Google Patents

Description

Meissner & Meissner 2756058

PATE NTANWALTS OFFICE BERLIN - MUNICH

- PATENT AGENCIES

^ DIPL-ING. W. MEISSNER (BLN)

DIPL-ING. P. E. MEISSNER (MCHN) DIPL-ING. H.-J. PRESTING (BLN)

HERBERTSTR. 22, 1000 BERLIN Your sign Your letter from the UnMr * sign Bariin, den

Mjr / Zi / Fall 12 480 December 8, 1977

Mannesmann Aktiengesellschaft, 4000 Düsseldorf 1, Mannesmannufer 2

"Process and system for the production of seamless tubes"

The invention relates to a method for producing seamless tubes according to the preamble of claim 1.

Such a push bench method is described in DT-OS 1 452 482- With the pipe push bench method today, the heated block is usually punched in a punch press and then in a subsequent one Stretching mill stretched to the outer and inner diameter required for the shaping process. The stretching happens by skew rolling with a shoulder rolling mill, also called Assel rolling mill, which works with an internal tool. The one while stretching The achievable reduction in the outer and inner diameter depends on the shoulder height and the outer diameter of the inner tool and thus kept within relatively narrow limits.

In addition, for reasons of tolerance of the product In the piercing press, the ratio of the pierced length to the piercing mandrel diameter should be greater than about 7.5: 1. The piercing mandrel diameter in turn depends on the pin diameter and the possible internal reduction of the stretching mill determined. Usually this is 8-16 mm.

Thus, the possible operating weight is determined for a certain push pin diameter. The result is that there is a boundary wall thickness for the specified maximum pipe length behind the bumper and the pipe length decreases with increasing wall thickness.

9 0 9 8? 4/0 3 7 8

275SÜ58

The object of the invention is to increase this boundary wall thickness to a significantly larger proportion of the production with maximum To be able to produce pipe length and thereby improve the warm extraction of the push bench system. The boundary conditions for the punch press, namely the length / diameter ratio cannot be changed. So there is only an increase in weight by increasing the block cross-section and an associated increase in the piercing mandrel diameter in question or in order to become a larger hollow block cross-section, the use of another Hole process, for example a piercing mill. For middle Plant sizes, however, a piercing mill is too expensive.

However, an enlarged block cross-section makes it necessary that the hollow block produced by the perforation passes through a perforation and stretching roller a second time, and finally on the one for the push bench suitable dimensional range to come. After, however, as stated in DT-OS 1 452 482, a stretching in a stretching mill can cause warping of the metal, a second or possibly even a third pass leads through a hole and Draw roller leads to an increased deterioration in the quality of the too generating product.

Thus, in addition to the general task of increasing the boundary wall thickness, there is also the task of creating a method which reduces the outside and inside diameter of the hollow block to the same extent in front of the push bench, without thereby creating any disadvantages for the quality of the product to be produced.

This object is achieved in that immediately before the push bench rolling a multi-stage continuous longitudinal rolling takes place.

909824/0378

This method is particularly suitable in connection with a previous punching by punching and stretching by skew rolling, in which the continuous longitudinal rolling is immediate takes place after the skew rolling.

A system for carrying out the method is characterized by this from that a multi-stand continuous longitudinal rolling mill is arranged in front of the push bench, which in one with a punch press and a three-roller piercing mill for stretching equipped plant between the three-roller piercing mill and the push bench is.

The continuous longitudinal rolling immediately before the push bench rolling leads to a high heat output with high quality of the pipes produced in the push bench, which in a known manner by rolling or Drawing can be brought to finished pipe dimensions.

The attached figure shows a system according to the invention in a schematic representation. A workpiece, not shown, runs through the system, as indicated by a dashed line with arrows Line 8 is shown. One coming from a furnace (not shown) usually a square block is punched in a punch press 1 and rounded in the process. From the punch press 1, the punched block enters a Three rolling rolling mill 2, the rollers of which have shoulders in a known manner and which with an internal tool that is in the hollow block provided with a bottom is introduced, is equipped. The elongated hollow block is now a five- or six-frame block continuous longitudinal rolling mill 3 supplied, which in a known manner is equipped with a group drive. The stretched tube billet, which is still provided with a bottom, is now fed to a push bench 4 and rolled out into a tube. At the end of the push bench 4 this will be The bottom end of the tube is cut off and the tube is then fed to an oven 5, from which it finally goes to a further continuous one Longitudinal rolling mill, a multi-stand stretch-reducing mill is fed. 24 - 28 scaffolds are the norm. From the stretch-reducing mill 6

909824/0378

the finished pipe finally arrives on a cooling bed 7.

During its passage, the workpiece acquires the following cross-sectional dimensions, for example. A Outside diameter of 295 mm and the inside diameter of 18o mm. In the three-roll piercing mill, the outer diameter is reduced to 245 mm and the inner diameter to 166 mm. In the continuous longitudinal rolling mill there is a further reduction in the Outside diameter to 214 mm and the inside diameter to 132 mm. Finally, a pipe with an outside diameter is produced in the push bench of 139 mm and an inner diameter of 130 mm.

- patent claims-

ORIGINAL INSPECTED 909824/0378

Claims (1)

2756Ü58 FaI I number 12 48ο Claims (ι.! method for producing seamless tube from blocks in Push bench rolling process, with the warm billets through The holes are formed into hollow blocks, the hollow blocks are stretched by rolling and then by the StoÄank rolling be rolled into tubes, characterized in that that immediately before the push bench rolling a multi-stage continuous longitudinal rolling takes place. ?. A method according to claim 1 for producing seamless tubes, in which the hot blocks are perforated and the hollow blocks are stretched by inclined rollers, characterized in that that the continuous longitudinal rolling immediately after Skew rolling takes place. 3. Plant for carrying out the method according to claim 1, with a push bench, characterized, that in front of the push bench (4) a multi-frame continuous Longitudinal rolling mill (3) is arranged. 4. Plant according to claim 3 for performing the method according to claim 2 with a punch press for punching the blocks, one this downstream three-roller piercing mill and the push bench downstream from the three-roller piercing mill, ORIGINAL INSPECTED 909824/0378 275SQ58 characterized in that the multi-stand continuous longitudinal rolling mill (3) between the three-roll rolling mill (2) and the Push bench (4) is arranged. Dipl .-: ..: / 0378