SK5472000A3 - Ladle nozzle for continuous casting - Google Patents

Abstract

The invention concerns continuous steel casting. It concerns a ladle nozzle for continuous casting comprising, in a downstream zone, a first part (3) with substantially constant cross-section and, upstream of said first part, a second part (4) with substantially divergent cross-section. The invention is particularly applicable to continuous steel casting.

Description

Technical field

The invention relates to a pipe intended for steel outflow from a ladle in continuous steel casting.

BACKGROUND OF THE INVENTION

Several types of tubes used in continuous casting mills are known which allow molten steel to flow out of the ladle toward the manifold. Among the very widespread types of these tubes are straight tubes as well as convergent tubes, Bell Shape tubes and Elephant Foot tubes.

Since it is essential that the steel outlet pipes of the casting ladle resist the aggressive effects of molten steel, they are made of durable refractory materials with high performance properties. The geometry of the molten steel discharge is very complex and subject to many variables. The outflow of molten steel is not uniform; as a result, pipe layers are often disrupted, particularly in those areas where the steel discharge rate decreases, with an overall average speed of the order of one meter per second. The whole procedure depends on many parameters, among others on the tube head (especially on the ladle shifter) and on the special tube. The casting dynamics of the steel cause vibrations, which are at the bottom stronger of the manifold geometry if the tube is convergent. Indeed, vibrations inevitably lead to stresses, which, together with the aggressiveness of the environment, can cause the pipe to break, especially when the pipe is firmly connected to the slider, and it is not possible to rotate it.

In the event that the steel discharge pipe cannot perform its function properly, it must be replaced, which is a difficult and costly operation that entails a number of practical difficulties, especially when it comes to the performance of the steel mill.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved molten steel discharge tube which does not have the above-mentioned disadvantages.

In addition, according to the invention, it should be possible to connect the pipe to a shank slider which closes the passage of the outlet from the shank to the pipe.

Each casting ladle filled with molten steel comprises a refractory sand plug which is sandwiched between the molten steel and the closure so as to include the outlet of the casting ladle. When this cap is opened, the cap must be removed by passing through the cap; the casting ladle must not be blocked in order to avoid any deflection of the pressure wave associated with the blow-back.

The invention further aims to allow the slider to be opened when the end of the pipe is immersed in the steel in the distributor without the risk of clogging.

Further, the invention aims to reduce the steel injection speed between the ladle and the manifold while maintaining the same power. The Applicant concludes that it is possible to suppress the unstable dynamic effects that occur when a steel jet strikes the manifold bottom, thus reducing or even eliminating unwanted tube vibrations and thus the risk of the tube being distorted or broken. In addition, the modification of the molten steel outflow structure also favorably influenced decanting in the manifold. The form of the tube also makes it possible to avoid blockage by the refractory sand which forms the plug of the ladle.

It is therefore an object of the present invention to provide an improved continuous steel pouring tube in a casting ladle, characterized in that a lower section of constant cross section is provided at the bottom which extends upwardly with a second section of relatively divergent cross section.

First, it should be noted that the first part with a substantially constant cross-section may be slightly divergent or convergent. A similar example is given below.

As for the second part, its cross-section is relatively divergent, which means it is more divergent than the first part. Its transverse inner bottom section is identical to the transverse lower section of the upper part of the first part, therefore a regular passage is formed.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will further be apparent from the description of the invention based on the following figures:

Fig. 1 shows a longitudinal section of one embodiment of a pipe according to the invention, and FIG. 2 shows a cross-section of the tube according to FIG. First

The figures represent only one possible embodiment, while the invention relates to a general solution. However, the figures serve both to better understand the invention and to define it.

description

Fig. 1 shows a longitudinal axial section of a continuous steel pouring pipe from a ladle with continuous casting which, as is customary, is provided with a connecting piece 6 for connection to a ladle and a circular variable cross-section pipe.

The pipe 2 consists of a first lower part 6 with a cross-section substantially constant on the distributor side and a second upper divergent part 6 on the side of the casting ladle. The pieces 6 and 6 are joined in a plane 6 where at least their internal cross-sections are identical.

In the illustrated embodiment, the first bottom panel 6 with a substantially constant cross-section is slightly divergent with an apex angle of 2 °. The second lower part 6 is divergent with an apex angle of 10 °.

In the embodiment shown, both the first lower part 3 and the second upper part 6 are substantially constant divergent and correspond to the shapes of the truncated cones.

As regards the internal design of the pipe, a different divergence may also be considered, e.g. instead of the truncated cone control line, an exponential curve or generally any curve can be applied provided that it defines the necessary divergence overall.

Moreover, the wall thickness of the tube in the first lower part 3 is preferably substantially constant. The same is true of the second upper part 6. However, the outer shape of the tube may be adapted as desired or as required not associated with the discharge of steel from the ladle.

It should also be noted that on the second upper part 4, the steel outflow tube from the casting ladle is formed by a part (near the connecting piece 1) which - as the first lower part 3 - has a substantially constant cross-section. they connect in the plane T where the lower cross-section of the part 6 is at least internally identical to the upper cross-section of the part 6.

Preferably, the left end of the tube is provided with a sheath-shaped sheet from the outside.

Preferably, the length of the first lower tube portion 3 is equal to three times its lower diameter. The length of the second bottom panel 6 is a function of its divergent angle and the desired steel outlet diameter.

The tube may be made of graphite alumina or other refractory materials usable in steel mill operations.

It has been observed that the molten steel entering the tube exits at a rate lower than the inlet rate. The ratio of the average discharge velocities is equal to the ratio of the cross-sections of the pipe and consequently the square of the diameters if the pipe has a circular cross-section. Due to the shape of the tube, there can be no solid, powdery or granular mass (especially mass

used on the stopper blocked. outflow hole) in any event The invention is particularly significant in case, when uses lejárskej slider pan. Tube shape je s preferably

adapted to the characteristics of the discharge from the ladle slider.

Although it would be desirable to make the pipe of the invention as a monoblock by isostatic pressing, it is preferred, at least in some cases, to make the pipe of two or more parts which are then fixedly connected in a known manner. However, some of these parts may preferably be formed by isostatic pressing.

In particular, the shapes, in particular the inner shapes, are very important, but the invention is not limited to an exemplary embodiment which can be appropriately modified by the skilled person, especially in terms of dimensions.

In the described embodiment, the first lower part 3 is divergent with an apex angle of 2 °. However, it is also possible to envisage another, preferably small or no or convergent angle, provided that it is less than 2 °.

Generally speaking, the second upper panel 4 is divergent with an apex angle between 1 ° and 20 °, preferably between 3 ° and 14 ° and preferably between 6 ° and 10 °.

The invention can also be applied when a different type of shutter or slider is used.

In general, the dimensions of the first lower portion 3 correspond to approximately one to five times its transverse dimension, preferably two to five times its transverse dimension, preferably about two to four times its largest transverse diameter.

The cross-sectional shape of the first lower panel 3 and the second upper panel 8 perpendicular to the axis may be any provided that sufficient continuity is maintained. However, oval, e.g. almost elliptical or, more precisely, a substantially circular shape.

Claims (10)

PATENT 1. A continuous casting steel discharge tube, characterized in that it consists in the lower part of a first part (3) with a substantially constant cross-section to which a second part (4) with a relatively divergent cross-section is connected upwards. Tube according to claim 1, characterized in that the average apex angle of the first part (3) is less than 2 °. Tube according to one of Claims 1 and 2, characterized in that the second part (4) is divergent with an apex angle between approximately 1 ° and 20 °. Tube according to claim 3, characterized in that the second part (4) is divergent with an apex angle between approximately 3 ° to 14 °. Tube according to claim 4, characterized in that the second part (4) is divergent with an apex angle between 6 ° and 10 °. Tube according to one of Claims 1 and 5, characterized in that the length of the first part (3) is equal to one to five times its largest transverse dimension. Tube according to claim 6, characterized in that the length of the first part (3) is equal to two to five times its largest transverse dimension. s a 8. The pipe laid by the double dimension. according to claim 7, characterized by the length of the first part (3) being up to four times the largest Tube according to one of Claims 1 to 8, characterized in that at least one of the first (3 (4) parts has a substantially oval cross-section Tube according to one of Claims 1 to 8, characterized in that at least one of the two (4) parts has a circular cross-section. : and is equal to its transverse and second f of the first (3) essentially