DE102016215130A1 - Rolling mill with a slanting mill according to the Asselverfahren - Google Patents

Abstract

The invention relates to a rolling mill, comprising a first rolling mill (1) in the form of a cross rolling mill for producing a seamless tube (2) over a mandrel rod (3) according to the Asselverfahren, wherein the seamless tube (2) after the first rolling mill (1) in a second rolling mill (6) is transferred for the purpose of post-processing, wherein the tube (2) in the second rolling mill (6) over a mandrel rod (3) is formed.

Description

The invention relates to a rolling mill according to the preamble of claim 1, a method for producing a seamless tube and a seamless tube.

EP 0 703 015 B1 describes a method for producing seamless pipes based on the Assel rolling process. In this case, a typical for the Asselverfahren spiral formation on the inside of the tube is to be reduced by a certain calibration of the rolls.

It is the object of the invention to provide a rolling mill, which allows the production of seamless pipes with a smooth inner wall.

This object is achieved according to the invention for a molding press mentioned above with the characterizing features of claim 1. By forming over a mandrel bar in the second rolling mill, a helix of the inner wall formed by the first rolling mill or Assel mill is reliably removed.

The invention is particularly suitable to upgrade existing, conventionally constructed Assel mill by the addition of the second mill so that the pipes produced high design requirements.

In the present case, a cross rolling mill according to the Assel method is understood to mean a conventional Assel rolling mill. As a rule, the tube is formed over a mandrel by means of several inclined rollers.

By forming over the mandrel in the second rolling mill a certain reduction of the wall thickness of the tube is achieved with simultaneous longitudinal stretching of the tube regularly.

In a generally preferred embodiment of the invention, the mandrel of the first mill remains in the transfer to the second mill in the tube and is used in the forming of the tube in the second rolling mill. As a result, only a total of a mandrel bar must be used for the production of the tube. In a preferred development, the mandrel bar is automatically returned to the first rolling mill after the forming in the second rolling mill. For this purpose, known chain conveyors can be used, for example.

In a preferred embodiment of the invention, the second rolling mill is designed as a longitudinal rolling mill. The longitudinal rolling mill particularly preferably has driven rollers.

In an advantageous detailed design, the second rolling mill is designed to carry out a rolling process with a mandrel moving relative to the pipe. Particularly preferably, this can be an MPM rolling process (MPM = multistand plug mill). This results in an optimal combination in terms of benefits and cost, especially when retrofitting existing Assel rolling.

In general, the forming in the second rolling mill advantageously smoothes an inner wall of the pipe. In particular, a helix of the inner wall produced by the first rolling mill is also reduced or eliminated.

In a preferred embodiment of the invention, a heating device for heating the tube is provided between the first rolling mill and the second rolling mill. This ensures compliance with the forming temperature for the second forming step in a simple manner. The heating device can be designed, for example, as an induction coil.

Generally, a reheating furnace and / or a reducing mill and / or a sizing mill are provided after the second rolling mill. Such stations are common in conventional Asselwalzanlagen. In the reducing mill and the sizing mill, there is generally no mandrel bar in the tube. Such stations for further reworking in Asselwalzanlagen usual. When upgrading an existing, conventional Asselwalzanlage with a second rolling mill according to the invention, these post-processing stations can remain and be used depending on the requirements of the tubes produced.

The object of the invention also for a method for producing a seamless tube by means of a rolling mill according to the invention by the features of claim 10.

The object of the invention is also achieved for a seamless tube, produced by means of a rolling mill according to the invention. Such a tube according to the invention is particularly preferably designed for use as an OCTG tube (OCTG = Oil Country Tubular Goods). Such OCTG tubes are subject to appropriate specifications and requirements by the oil industry, in particular with respect to the properties of an inner wall.

Further advantages and features will become apparent from the embodiment described below and from the dependent claims.

Hereinafter, a preferred embodiment of the invention will be described and explained in more detail with reference to the accompanying drawings.

1 shows a partial view of a rolling mill according to the invention during the transfer of a pipe from a first rolling mill to a second rolling mill.

2 shows the rolling mill 1 during a forming of the tube in the second rolling mill.

In the 1 The rolling mill according to the invention shown comprises a first rolling mill in the form of a cross rolling mill 1 for making a seamless pipe 2 after the Asselverfahren. This is the tube 2 above a mandrel located therein 3 rolled or formed.

After the first forming, the pipe becomes 2 in its longitudinal direction in a discharge area 4 of the cross rolling mill or Assel mill 1 applied. There is a device for transverse transport 5 arranged, by means of the outgoing pipe 2 together with the mandrel still arranged therein 3 is offset transversely to the outlet direction.

A second rolling mill 6 is in line with the end of the transverse transport device 5 arranged. In the present case, this is a longitudinal rolling mill for carrying out an MPM rolling process. At least some of the rollers 6a of the second rolling mill are driven. They run transversely or at right angles to the tube 2 ,

This is the tube 2 deformed therein mandrel, so that a change in the wall thickness takes place and in particular one in the first rolling mill 1 resulting helix on the inner wall of the tube 2 is smoothed. In this case, the mandrel is here 3 with opposite the pipe 2 moved deviating speed, so that takes place at the same time as the rolling of the tube over the mandrel rod, a pulling out of the mandrel rod from the tube.

For this purpose, the mandrel is 3 after the cross transport 5 on an end-side handle part 3a from an axial rod holder 7 detected. The axial rod holder may comprise a hydraulic cylinder, in particular a bidirectional cylinder.

Below is the tube 2 in the second rolling mill 6 introduced and rolled while the mandrel 3 by means of the hydraulic axial rod holder 7 is moved in a controlled manner. The mandrel moves 3 in the longitudinal direction relative to the tube 2 so that, at the same time as rolling, at least a partial separation of the mandrel bar from the tube 2 he follows.

After complete rolling and pulling out of the mandrel bar 3 becomes the pipe 2 transferred to the left to further processing stations (not shown). This is a reheating furnace followed by a reduction mill, followed by a sizing mill.

The pulled-out mandrel 3 is by means of a rod retract driver 8th to a chain puller 9 passed, after which the mandrel automatically in the manner of a cycle to the first mill 1 is returned.

In the present case, the first rolling mill and optionally the chain extractor as well as the aforementioned further processing stations are components of an existing Assel rolling plant. The second rolling mill 6 is retrofitted in this rolling mill to increase the product portfolio of the rolling mill. In particular, this is the production of OCTG tubes 2 made possible by means of the upgraded rolling mill.

LIST OF REFERENCE NUMBERS

1

 first rolling mill, cross rolling mill after the Asselverfahren

2

 pipe

3

 mandrel

3a

 Handle part of the mandrel

4

 Outflow area of the first rolling mill

5

 cross transport

6

 Second rolling mill, longitudinal rolling mill according to MPM method

6a

 driven rollers

7

 Axialstangenhalter

8th

 Rod withdrawal driver

9

 Kettenauszieher

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 0703015 B1 [0002]

Claims (11)

Walzanlange, comprising a first rolling mill ( 1 ) in the form of a cross rolling mill for the production of a seamless tube ( 2 ) over a mandrel bar ( 3 ) according to the Assel method, whereby the seamless tube ( 2 ) after the first rolling mill ( 1 ) in a second rolling mill ( 6 ) is handed over for the purpose of a post-processing, characterized in that the pipe ( 2 ) in the second rolling mill ( 6 ) over a mandrel bar ( 3 ) is transformed. Rolling plant according to claim 1, characterized in that the mandrel bar ( 3 ) of the first rolling mill ( 1 ) during the transfer to the second rolling mill ( 6 ) in the pipe ( 2 ) and during the forming of the tube ( 2 ) in the second rolling mill ( 6 ) is used. Rolling plant according to claim 2, characterized in that the mandrel bar ( 3 ) after forming in the second rolling mill ( 6 ) automated to the first rolling mill ( 1 ) is returned. Rolling plant according to one of claims 1 to 3, characterized in that the second rolling mill ( 6 ) is formed as a longitudinal rolling mill. Rolling plant according to claim 4, characterized in that the longitudinal rolling mill via driven rollers ( 6a ). Rolling plant according to one of claims 4 or 5, characterized in that the second rolling mill ( 6 ) for carrying out a rolling process with respect to the pipe ( 2 ) moving mandrel ( 3 ), in particular an MPM rolling process is formed. Rolling plant according to one of the preceding claims, characterized in that the deformation in the second rolling mill ( 6 ) a smoothing of an inner wall of the tube ( 2 ) causes. Rolling mill according to one of the preceding claims, characterized in that between the first rolling mill ( 1 ) and the second rolling mill ( 6 ) a heating device for heating the pipe ( 2 ) is provided. Rolling plant according to one of the preceding claims, characterized in that after the second rolling mill ( 6 ) a reheating furnace and / or a Reduzierwalzwerk and / or a sizing mill are provided. Method for producing a seamless pipe by means of a rolling mill according to one of the preceding claims, comprising the steps of - forming the pipe ( 2 ) by means of the first rolling mill ( 1 ), and - smoothing an inner wall of the tube ( 2 ) by means of the second rolling mill ( 6 ). Seamless pipe ( 2 ), in particular for use as an OCTG tube, produced by means of a rolling plant according to one of claims 1 to 10.

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