LU82361A1 - IMPROVEMENTS IN THE CONTINUOUS CASTING PROCESS FOR METALS AND DEVICE FOR CARRYING OUT SAID METHOD - Google Patents

Description

I * ^ I C 2028/8004.

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METALLURGICAL RESEARCH CENTER -j CENTRUM V00R RESEARCH IN DE METALLURGIE,; Non-profit association - vereniging zonder winstoogmerk i in BRUXELLES, (Belgium).

, Improvements to the continuous metal casting process and device for implementing this process.

The present invention relates to improvements to the process for the continuous casting of metals and especially of steel.

! It is known that in the continuous casting methods of metals, such as for example steel, the metal produced is cast in a suitable container, called a distribution basket, out of which it flows continuously in a casting mold, j 1 via an oarticular outlet tube known scus leV / r 1 2.- name of nozzle. When the steel is cast in a relatively large format, the steel-air interface is protected by a melting powder and, under these conditions, during the entire casting operation, the lower end of this nozzle dips below the level of the metal contained in the mold.

The nozzle is most often made up of a combination of refractory materials whose melting point is particularly high.

k Such a nozzle must withstand not only the thermal stresses due to the temperature of the cast metal, but also to any chemical attack which may arise therefrom, to the mechanical effects due to the movements of the metal bath and to the erosion by the powder. cover generally deposited on the upper surface of the liquid metal located in the mold.

To make it possible for the metal to flow out of the nozzle, the latter is provided, at its lower end, with an outlet orifice of suitable dimensions.

In order to accentuate the movement of the liquid metal, at least in the upper part of the continuous casting ingot mold, it has already been imagined to provide the lower part of the nozzle, not with an axial orifice, but with several lateral orifices, by each of which the liquid metal flows in the ingot mold, thus modifying the movements of the liquid metal therein and improving the quality of the solidified metal.

However, it is important that the use of such nozzles does not lead to two significant drawbacks, easily encountered in these continuous casting processes, namely on the one hand, the surface cleanliness defects, in particular by surface incorporation of non-metallic inclusions. such as alumina and on the other hand, poor conditions for solidification of the metal, mainly at the upper part of the mold where the thickness of the solidified metal wall is still small, which can subsequently lead to the formation of defects / superficial, such as cracks or even a hole in the neck / r Λ 3.- It is precisely these two drawbacks that we succeed in reducing, in a significant proportion, thanks to the process which is the subject of the present invention.

This process of continuous casting of metals, in the-j; which one makes use of a pouring nozzle arranged under the basket | distributor and whose lower end, provided with one or more lateral orifices is immersed in the liquid part of the metal located in the continuous casting mold, is essentially characterized in that the said nozzle, at least as regards „ its lower part, comprising the submerged portion as well as the lower section of its non-submerged portion, is subjected to a movement such that the metal outlet orifices travel a path which can be closed and of which at least the major part i is substantially horizontal.

According to an advantageous method of the above method, the movement imparted to the lower part of the nozzle is a rotational movement, with a substantially vertical axis, the said movement being able to be circular, in one direction, or alternately in both directions, continuous , or intermittent.

The characteristics of the path printed on the lower part of the nozzle are chosen so that the thickness of the wall of the ingot, against which the liquid metal currents are directed, is as constant as possible at the same level of the ingot mold and uniformly increasing towards the bottom of it.

The amplitude of the rotation printed at the party! t lower of the nozzle is in connection with the shape of the ingot; the more the shape of the cross section of the ingot approaches the square, the greater the amplitude of this rotation can advantageously be, until waiting at least 180 ° in one direction (the rotation can then be continuous), the more the shape of the said section approaches an elongated rectangle, the smaller the amplitude of the angle of rotation and approaches the angle below the small side of the rectangle is seen from the point of piercing of: j 4 .- r 1 upper surface of the liquid metal by the axis of rotation of the nozzle.

It was found, which was not obvious, that this movement imprinted on the lower part of the nozzle favored the ascent of non-metallic inclusions in the metal, thus contributing to the inclusion cleanliness of the ingots, the washing of the solidified skin. being effectively ensured by a better distribution of the jet of liquid steel.

The present invention also relates to a * device, in this case a nozzle, for implementing the methods described above.

This nozzle is essentially characterized in that its lower part consisting of the portion intended to be immersed, and at least the lowest section of its non-submerged part, are provided with means for subjecting them to a relative movement relative to its upper part or in relation to the distribution basket.

The envisaged movement will advantageously be rotary / circular, around the axis of the non-rotating part of the nozzle. / h

Claims (6)

1. Continuous metal casting method, in which use is made of a pouring nozzle disposed under the distribution basket and the lower end of which, provided with several lateral orifices, is immersed in the bath of metal. continuous casting ingot mold, characterized in that said nozzle, at least as regards its lower part comprising the immersed portion as well as the lowest section of its non-submerged portion, is subjected to a movement such that the outlet orifices of metal travel a path which can be closed and at least the major part of which is substantially horizontal. 2. Method according to claim 1, characterized in that the movement imparted to the lower part of the nozzle is a rotary movement, with a substantially vertical axis, the said movement possibly being circular, in one direction, or alternately in both directions , continuous, or intermittent. 3. Method according to either of claims 1 and 2, characterized in that the path printed on the lower part of the nozzle is chosen such that the thickness of the wall of the ingot against which the metallic currents leaving the nozzle are directed, ie as constant as possible at the same level of the ingot mold, and uniformly increasing towards the bottom of the latter. 4. Nozzle for the implementation of the processes! listed in any one of claims 1 to 3, characterized! . . in that its lower part at least comprises these means, set in motion relative to its upper part or by rat- / I. /./ port to the distribution basket. '// W'. \ ΐ 6.- ΐ! 5. Nozzle according to claim 4, character- | laughed at in that the said means are such that most of the | less of the movement takes place in a horizontal plane. 6. Nozzle according to either of Claims 4 and 5, characterized in that the movement is a rotational movement. T: L: os? - ;;. A. - (- f 1 „..J, ....... cirt: ^! '~ .. H - · -: - ··· ··' npvc-! .... ps' * ·, j ri? re'ver.o'ca: or;. / i.urérfé cescnpM I [U "“ Trouer, ^! C n - r '- ε ilur ~ ra r. * iiiiii [1