GB2117293A

GB2117293A - Process for the production of a tubular mould for continuous casting

Info

Publication number: GB2117293A
Application number: GB08308318A
Authority: GB
Inventors: Horst Gravemann; Hermann Brunemann
Original assignee: KM Kabelmetal AG
Current assignee: KM Kabelmetal AG
Priority date: 1982-03-27
Filing date: 1983-03-25
Publication date: 1983-10-12
Also published as: ATA58683A; JPS58202984A; FR2523881B1; DE3211440C2; SE8301650D0; IT1160490B; CH659013A5; JPH0435269B2; FR2523881A1; IT8319904A0; SE8301650L; GB2117293B; AT386141B; DE3211440A1; GB8308318D0

Abstract

In the production of a tubular mould for the continuous casting, e.g. of steel, made of copper or a copper alloy, a flange (2) is attached to one end of a pipe (1) by electron beam welding. This method of welding produces a weld seam which, in contrast to welding methods previously used, is extremely narrow and which therefore does not appreciably affect the hardness of the pipe (1) where this has previously been hardened by cold working, and does not produce any appreciable distortion of the pipe (1) and/or flange (2). By suitable shaping of the flange (2) and/or the end of the pipe (1), welding can be effected either at the end face of the pipe, (as shown), or peripherally. <IMAGE>

Description

SPECIFICATION Process for the production of a tubular mould for continuous casting This invention relates to a process for the production of a tubular mould made of copper or a copper alloy for use in continuous casting, the mould comprising a pipe having a flange or flanges welded to one or both ends thereof, the pipe being first produced and the flange or flanges subsequently being attached thereto by welding.

In various vertical continuous casting systems and, in particular, in horizontal continuous casting systems in which the moulds are directly attached by means of flanges to a vessel for melting the metal to cast, or to a vessel in which the melt is held, tubular moulds are use which have a circular of polygonal cross-section and which has a flange or respective flanges attached to one thereof, the diameter of the or each flange being appreciably greater than the pipe diameter in the case of a circular pipe, or the diagonal in the case of polygonal pipes.

Hitherto, the production of such copper or copper alloy moulds has been carried out exclusively by machining a forged or extruded solid body, or by welding a flange on to a previously manuactured pipe by means of gas shielded welding.

It is only possible to use the welding process in the case of types of pure copper which can easily be welded, such as SF-copper and SE-copper, or in the case of low-alloying constituent copper alloys such as Cu Ag 0.1 P. Moulds produced in this way were found to have substantial disadvantages since the mould pipe which was originally hardened by cold working resolidified to a soft condition as a result of the attachment of the flange, by welding, which led to severe warping, and the welding seam which was located in the zone subject to the highest thermal loading represented a substantial risk factor since, even with optimum welding seam qualities, leakages could not be ruled out as a result of pores and thermal fatigue during use. In addition, the poor stability as regards shape resulted in a service life of one to at the most five hours for the casting of steel.

Although the production of flanged moulds from solid blocks made of the copper types referred to above makes it possible to eliminate the dangers represented by the presence of a welding seam, since the solid body required for this process could not be adequately hardened by cold working, no improvement in service life is in fact achieved, in comparison with welded pipes.

Moreover, the production of such pipes necessitated a considerably operational outlay.

It is possible to obtain a definite increase in service life by the production of moulds from lowalloying constituent, hardenable copper alloys. In this case also, it was necessary to produce the tubular moulds from a solid body of material since these materials basically cannot be welded by gas shielded welding because of their liability to crack.

Even in the case of a solid body of material, high stability values can be obtained with the materials in question by thermal treatment (hardening), so that the tubular moulds exhibit a correspondingly good stability as regards their shape and good wear resistance. However, the high production outlay leads to high costs, which make it doubtful whether the use of tubular moulds so produced is viable in horizontal continuous casting.

It is an object of the present invention to provide a process for the production of tubular casting moulds having a flange arranged at at least one end thereof, which is economical in operation and does not involve any softening of a mould which has previously been hardened by cold working, and which facilitates the production of tubular moulds made of hardened copper alloys in which a flange is attached at one or both ends.

According to the invention, there is provided a process for the production of a tubular mould for use in continuous casting, made of copper or a copper alloy and having a flange attached by welding to at least one end thereof, comprising the steps of first producing a pipe and thereafter attaching the or each said flange to the end or respective ends thereof by electron beam welding.

The or each flange is preferably made of the same material as the pipe.

An essential advantage of the use of electron beam welding in accordance with the invention consists in that, during the electron beam welding, the components being welded undergo virtually no warping and only in an extremely narrow welding zone is the hardening lost. In the flanged tubular moulds produced by the process of the invention, the original dimensions and the hardness produced as a result of the cold working are not appreciably affected.

In carrying out the process of the invention, the mould pipe is first externally turned or milled off at one end at least, and the flange is positioned upon the turned or milled end, and subsequently the flange and the pipe are welded together from the front. In this process, the welding seam is positioned outside of the wall of the pipe wall which is particularly endangered by the bath surface region.

In a further form of process in accordance with the invention, a flange element having a part whose outer and inner dimensions correspond to the corresponding dimensions of the wall of mould pipe is positioned on the end of the pipe, an adjusting member positioned on the flange element, is inserted into the end of the mould pipe, and the flange element and the mould pipe are welded to one another by a seam running in the peripheral direction. The outer dimensions of the adjusting member, which simultaneously serves an electron beam trap correspond to the inner dimensions of the mould pipe and of the flange element thus preventing displacement occurring when the flange is welded to the mould pipe. After the welding is completed the adjusting member is removed from the finished mould.

Flanged tubular moulds produced by the process of the invention have been found to have service lives for the casting of steel, which are double or more than that of the pure copper flanged moulds previously used.

The process of the invention can also be used with particular advantage for the production of flanged tubular moulds consisting of hardenable copper alloys, such as, for example, CuCr, CuCrZr, CuZr, CuCo/NiBe and CuNiP. As regards materials which are partially sensitive to cracking, electron beam welding can be used to achieve absolutely perfect welding seams which where necessary, even permit subsequent calibration of the finished mould by explosive forming. The optimum properties of these materials, and, in particular, their high degrees of hardness and stability to heat, remain virtually unaffected by the electron beam welding.

The invention will now be further described with reference to the drawings, in which: Figure 1 is a schematic side-sectional view of one end of a tubular mould produced by a process according to the invention; Figure 2 is an end view of the mould of Figure 1; Figure 3 is a view similar to that of Figure 1 of another pipe mould produced by a process according to the invention immediately after the production of the welding seam; and Figure 4 is a view similar to that of Figure 1 of a further pipe mould produced by a process in accordance with the invention.

Referring to Figure 1, in order to prepare for the welding process a specific region of the end of a mould pipe 1 is removed by turning in the case of a circular pipe, or in the case of a square pipe, as illustrated, by milling, and a flange 2 is inverted over the opening, the inner wall of the flange abutting against a shoulder formed by the turning or milling operation. From the end of the mould, a welding seam 3 is then produced by electron beam welding so as to weld the pipe 1 and the flange 2 together. If necessary, a region 4, shown shaded, on the inner side of the flange 2 can subsequently be removed. However, it is also prossible to produce a flange 2 with a projection 5 for attachment to the end of the pipe 1, and to connect the flange 2 and the pipe attachment projection 5 to the mould pipe 1 by electron beam welding.Under certain circumstances, the gap 8 which remains between the mould pipe 1 and the pipe attachment projection 5 can be closed by electron beam welding using a welding seam running in the peripheral direction.

In the tubular mould illustrated in Figure 3, a flange 2a provided with a projection 5a for attachment to a pipe 1, and the end face of which corresponds to the end face of the pipe 1, is positioned on the end of the mould pipe 1, and an adjusting member 6 which ensures that the flange 2a is exactly aligned with the mould pipe 1 is introduced into the end of the mould pipe 1. In this case, the welding seam 3, produced by electron beam welding, runs in the peripheral direction. The adjusting member 6 serves simultaneously as a trap for the electron beam.

Figure 4 represents a tubular mould produced by a process in which a flange 2b having a projection Sb for attachment to the pipe is positioned on the end of the pipe 1, the flange 2b having smaller internal cross-sectional dimensions than the pipe 1. In this case also, the welding seam 3 runs in the peripheral direction. The inner wall of the flange 2b is provided with a projection 7 serving as a trap for the electron beam, but the welding device may, if desired, be set in such a manner that the projection 7 is melted away during the welding. The internal dimensions of the flange 2b can be made to correspond to the inner dimensions of the mould pipe 1, although in many applications a mould pipe which possesses a smaller cross-section at the input in the region of the flange 2b is desirable.

If necessary, the moulds produced by the process of the invention can subsequently be calibrated, for example, by explosive forming.

The process of the invention is suitable for use in producing both moulds of circular cross-sectior and for those of polygonal cross-section e.g.

square or hexagonal cross-section.

With a mould in which the mould pipe 1 and the flange 2 were produced from the material CuCrZr having a hardness of 125HB and an internal dimension of 110 mm, during the casting of steel in a horizontal continuous casting system, a service life of above 100 hours with double refinishing was achieved.

Claims

1. A process for the production of a tubular mould for use in continuous casting, made of copper or a copper alloy and having a flange attached by welding to at least one end thereof, comprising the steps of first producing a pipe and thereafter attaching the or each said flange to the end or respective ends thereof by electron beam welding.

2. A process as claimed in Claim 1 , wherein said pipe and said flange or flanges are made of the same material.

3. A process as claimed in Claim 1, wherein the or each end of said pipe initially is externally cut away by turning or milling, a flange is positioned on the or each turned or milled end, and the or each flange and the pipe are welded together from the end face of the pipe.

4. A process as claimed in Claim 1, wherein a flange having a projecting part whose outer and inner dimensions and shape correspond to the dimensions and shape of the end of the pipe is positioned on the end of the pipe, and adjusting element is inserted into the end of the pipe over the flange, so as to hold the flange projection in place on the end of the pipe, and the flange projection and the pipe are welded to one another by a seam running in the peripheral direction.

5. A process as claimed in any one of the preceding Claims, wherein after the welding of the flange or flanges to the tube, the tubular mould formed is subsequently calibrated, preferably by explosive forming.

6. A process for the production of a tublar mould for use in continuous casting, substantially as hereinbefore described with reference to Figures 1 and 2, or Figure 3, or Figure 4, of the drawings.

7. A tubular mould for use in continuous casting, produced by a process as claimed in any one of Claims 1 to 6.