METHOD AND SYSTEM FOR THE PRODUCTION OF A SEAMLESS HOT-ROLLED TUBE AS WELL AS A ROLLED CENTRIFUGALLY CAST TUBE AND USE OF A HOLLOW BLOCK PRODUCED BY MEANS OF CENTRIFUGAL CASTING

Abstract

Sensitive hollow blocks or tubes are elongated in a hot-forming elongator while maintaining, if possible, the internal structure that is present or that forms immediately after casting, and thereby, in the case of suitable method management, even thin-walled tubes or tubes rolled from centrifugally cast hollow blocks can be made available to a sufficiently operationally reliable extent. As a result, for the first time, it is possible for rolled centrifugally cast composite material tubes to be made available and for composite material hollow. blocks produced using centrifugal casting to be utilized for the production of a seamless tube.

Claims

1. A production method for producing a seamless hot-rolled tube comprising: elongating a cast hollow block in a hot-forming elongator with an elongation of 10 or less; including one of the following: (i) circumventing a cross-roll piercing step or interposing a cross-roll piercing step at an elongation below 1.5; (ii) utilizing at least part of the casting heat; or (iii) utilizing at least part of the casting heat and circumventing a cross-roll piercing step or interposing a cross-roll piercing step at an elongation below 1.5.

2. The production method according to claim 1, wherein the hollow block is heated before elongation in the elongator, tempered in a furnace as a buffer, or heated before elongation in the elongator and tempered in a furnace as a buffer.

3. The production method according to claim 1, wherein after elongation, the hollow block is calibrated in a calibration unit.

4. The production method according to claim 1, wherein said cast hollow block is elongated in the hot-forming elongator with an elongation of 8 or less.

5. The production method according to claim 4, wherein said cast hollow block is elongated in the hot-forming elongator with an elongation of 7 or less.

6. The production method according to claim 1, wherein the elongator is a longitudinal rolling mill.

7. The production method according to claim 6, wherein said longitudinal rolling mill is a push bench.

8. A production system for producing a seamless hot-rolled tube comprising: (a) a hollow-block casting unit; (b) an elongator disposed behind the hollow-block casting unit; and (c) a conveying segment between the hollow-block casting unit and the elongator; wherein said conveying segment is sufficiently short so that part of the casting heat can be utilized for elongation in the elongator; and wherein said conveying segment is interrupted by a furnace, or runs without interruption and has a lock system to and from a furnace, or is interrupted at most by a severing unit.

9. The production system according to claim 8, wherein the furnace serves as at least one of a buffer, a reheater, and a temperature equalizer.

10. The production system according to claim 8, wherein the hollow-block casting unit is a centrifugal casting unit.

11. The production system according to claim 8, wherein the elongator is followed by a calibration unit.

12. The production system according to claim 11, wherein the calibration unit comprises at least one of a sizing mill and an elongation reduction unit.

13. The production system according to claim 8, wherein the elongator is a longitudinal rolling mill.

14. The production system according to claim 13, wherein the longitudinal rolling mill is a push bench.

15. The production system according to claim 13, wherein the longitudinal rolling mill has an elongation of 2 or more and of 8 or less.

16. A rolled centrifugally cast tube comprising a hot-rolled centrifugally cast composite material tube.

17. A seamless hot-rolled centrifugally cast composite material tube produced using a composite material hollow block produced by centrifugal casting.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Other objects, features, advantages, goals, and properties of the invention will become apparent from the following detailed description considered in connection with the accompanying drawings and exemplary embodiments. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention.

[0046] In the drawings,

[0047] FIG. 1 shows different variants with regard to production systems and methods for the production of a seamless hot-rolled tube; and

[0048] FIG. 2 is a schematic cross-section through a centrifugally cast composite material tube.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0049] The production system for the production of seamless hot-rolled tubes shown schematically in FIG. 1 first of all comprises a hollow-block casting unit 10, which is followed by an elongator 20 over a conveying segment 41, 42. The elongator 20 is followed by a calibration unit 30 over a conveying segment 43, so that a hot-rolled tube can be made available from a cast block, by way of the elongator 20 and the calibration unit 30.

[0050] In this regard, the conveying segment 41, 42 is configured to be so short that the casting heat can be utilized during elongation, as well. As is evident, there is no cross-roll piercing mill between the hollow-block casting unit 10 and the elongator 20, wherein—if necessary—a cross-roll piercing mill having a slight elongation, for example of 1.2 to 1.4, can be provided here.

[0051] A furnace 50 is provided in the conveying segment 41, 42 between the hollow-block casting unit 10 and the elongator 20. Preferably, the furnace 50 is situated not directly in the conveying segment 41, 42, but rather a lock system is provided, through which the cast hollow blocks can be moved out of the conveying segment 41, 42 and back into it again. Accordingly, working pieces might reach the elongator 20 directly, bypassing the furnace 50, which is enabling a direct use of the casting heat and, by the way, which is positive with respect to the use of energy. The working pieces might be tempered or kept at temperature within the furnace 50. In alternative embodiments, a lock system might be omitted so that every hollow block is passing through the furnace 50 with some working pieces having appropriate temperatures, passing through the furnace 50 to the elongator 20 very fast, if necessary.

[0052] In particular, rotary hearth furnaces 51, reverbatory furnaces 52 or induction furnaces 53 can be used as a furnace 50.

[0053] If considered necessary, a reheating furnace 54 can be provided in the conveying segment 43 between the elongator 20 and the calibration unit 30.

[0054] Likewise, it is possible that a severing unit (not shown) is also provided in the conveying segment 43.

[0055] In particular, a horizontal discontinuous centrifugal casting unit 11 or a vertical continuous centrifugal casting unit 12 is possible as a hollow-block casting unit 10. In general, the discontinuous centrifugal casting unit 11, just like other discontinuous casting units, will not require a severing unit for severing the cast hollow blocks if the subsequent system stages are appropriately coordinated with the casting unit.

[0056] In the vertical continuous centrifugal casting unit 12, as shown schematically in the sketch, a saw is provided, wherein the cut-off pieces are then removed and transferred to the conveying segment 41. It is also conceivable that the continuous centrifugal casting unit is tilted to allow discharge of the hollow blocks. Here, too, a severing unit can be provided, if necessary.

[0057] Furthermore, horizontally terminating hollow-extrusion units 13 or vertical hollow-extrusion units 14 can also be used as a hollow-block casting unit 10; in general, they are followed by a severing unit 60 after a conveying segment 44. In the present exemplary embodiment, this unit is provided as a saw 61, wherein here, of course, other severing units, with which hollow blocks can be severed with sufficient speed, can be provided.

[0058] It is understood that if necessary, horizontal continuous centrifugal casting units can be used as a hollow-block casting unit 10, behind which units a severing unit 60 can be provided after a conveying segment 44.

[0059] In particular, longitudinal rolling mills 21 are used as an elongator 20, for example a push bench 22, a plug rolling mill 24 or a continuous rolling mill 25. Likewise, a hot pilger rolling mill 23 can be used as an elongator 20.

[0060] In particular, sizing rolling mills 33 or elongation reduction rolling mills 32 are possibilities as a calibration unit 30.

[0061] The production system presented above, as well as a corresponding production method, are particularly suitable as hollow-block casting units 10 in connection with centrifugal casting units 11, 12. By means of centrifugal casting, it is possible to produce multilayer or bimetallic centrifugally cast hollow blocks, which can be hot-rolled on the production system 40 for the production of a seamless hot-rolled tube 70 and by means of corresponding methods. In this way, a tube 70 as shown in FIG. 2 can then be made available as a centrifugally cast tube 71, which has an outer material layer 73 and an inner material layer 74 composed of different materials and having different material properties. Because of the production process and particularly also because of the hot-rolling process in the elongator 20, a mixed layer 75 occurs between the outer material layer 73 and the inner material layer 74. Because of the hot-rolling process in the elongator 20, a hot-rolled centrifugally cast composite material tube 72 is therefore obtained, which has bimetallic properties if the method is managed appropriately.

[0062] With regard to concrete method management, it is ensured in the exemplary embodiments that the elongator works at elongations between 2 and 10.

[0063] Although only a few embodiments of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.