EP0683706B1 - Casting tube - Google Patents

Abstract

A reinforced casting tube with a collar (9) around which are formed thicker wall portions than the walls of another cross section of the tubular member. Apart from this thickened ceramic portion, another thickened portion may be provided in the moving direction of the tube so that the tubular member of the tube has an oblong cross section.

Description

The present invention relates to a pouring tube comprising a tubular element having at an upper end, a perfectly flat upper face intended to slide in a device for feeding and changing the tube or a regulating device along the fixed underside of a reference or movable refractory plate of a drawer plate, the assembly of the upper end of the tubular element being reinforced by a collar and by a metal protective casing.

It is intended for the production of pouring tubes used mainly in the steel industry, in particular in continuous casting installations. Its purpose is to mechanically reinforce the pouring tubes. These reinforced tubes thus reduce the risk of mechanical damage during tube changes during the same casting sequence.

Document WO 89/02800 discloses a pouring tube for a sliding closure device formed from two separate parts generally made of different refractory ceramic materials. The first part is a sliding tube plate made of alumina or magnesia, having a perfectly flat upper face intended to slide along a sliding plane, and the second part is a cylindrical tubular element provided with a flange integral with the tubular element intended to be immersed in a mold. The plate is attached to the tubular element by juxtaposition. The clamping face of the seal between the insert plate and the flange is flat or interlocking. It is generally a simple nesting. The flange and an upper part of the tubular element are covered with a protective metal casing, while the attached plate and the flank of the flange are enclosed in a hoop ring. This embodiment in two separate parts, one of which is a plate, makes it possible to machine the sliding surface by grinding. A perfectly smooth sliding surface minimizes metal infiltration into the sliding plane.

The advantage of this composite tube lies in the fact that the production of two flat surfaces is easier than that of an annular projection and a complementary groove.

According to this document, sufficient flatness is obtained by rectification.

Document FR-A-2241359 also discloses a submerged pouring tube having a channel of elliptical section, the wall of which has an increased thickness at the level of the major axis. This additional thickness is constant over the entire length of the pouring tube.

In this document, the great risk of rupture of the lower part of the pouring tube is described at the level of the lateral discharge orifices but not at the level of the collar.

Similarly, from document FR-A-1447139, there is known a process and device for the direct casting of metals for the production of narrow slabs. It is proposed to form an oval casting jet by the use of an oval-conical nozzle.

The oval-conical nozzle has a cross section of oval external shape as well as a flow channel of internal section of similar oval shape so that at the same section, the thickness of the wall is the same in all directions.

However, experience shows that due to the extreme stresses that the refractory material undergoes when the tube is changed, the pouring tubes are weakened at the location of the collar.

Vulnerable part of known pouring tubes is located at the level of the collar. This is where the mechanical reaction torque is exerted when changing the tube. The plunging part of the tube moved parallel to itself from the standby position to the service position is in fact held back by the viscosity of the molten metal bath in the mold.

To remedy this, it has been proposed to increase the thickness of the tubes of the cylindrical element, but the contingencies of the devices for feeding and exchanging the pouring tubes, the excessive weight of the tubes and the little space available under the metallurgical container prevents having greater thicknesses.

The present invention aims to solve this problem and provides a tube as described in the first paragraph of this specification.

The solution according to the invention consists in reinforcing the thickness of the tube not over the entire periphery and the entire length of the tubular element, but only in the most stressed places.

For this purpose, the present tube has at the collar and more particularly in the portions of walls oriented in the direction of movement of the tube, in order to reduce the risks of tube rupture, at the collar, an excess thickness of ceramic material by compared to the thickness of material at another cross section of the tubular element.

The collar is conical and of oblong cross section.

In the proposed embodiment, the collar is flush with the front and rear edges of the upper face, while it is set back from the lateral edges of said upper face. Therefore, the side flanges are free and can bear on the mechanical tube changing device.

The oblong shape of the collar in the direction of movement contributes to reinforcing its mechanical resistance to the thrust exerted by the rod when changing the pouring tube.

The oblong section serves to increase the moment of inertia and thereby reduce the risk of rupture.

When the tubular element comprises, integral with it, an anchoring flange intended to fix an added plate, made of a refractory material different from the tubular element and subjected to a rectification in order to be better adapted to slide against the plate reference, the reinforcing collar is integral with said anchoring flange.

Similarly, when the insert plate and the tubular element are in one piece, the collar is integral with them.

The features and details of the invention, as well as other characteristics will become apparent during the following detailed description of a particular embodiment of the pouring tube according to the invention, given by way of illustration and not limitation.

• la figure 1 est une vue en coupe longitudinale d'un tube de coulée selon l'invention;
• la figure 2 est une vue en plan d'une plaque réfractaire rapportée au tube;
• la figure 3 est une vue en coupe transversale du tube de coulée montré dans la figure 1;
• la figure 4 est une vue de dessous du tube de coulée montré dans les figures 1 et 3;
• la figure 5 est une vue en coupe longitudinale d'une seconde forme de réalisation d'un tube de coulée selon l'invention; et
• la figure 6 est une vue en coupe transversale du tube montré dans la figure 5.

This description refers to the attached drawings, in which:

• Figure 1 is a longitudinal sectional view of a pouring tube according to the invention;
• Figure 2 is a plan view of a refractory plate attached to the tube;
• Figure 3 is a cross-sectional view of the pouring tube shown in Figure 1;
• Figure 4 is a bottom view of the pouring tube shown in Figures 1 and 3;
• Figure 5 is a longitudinal sectional view of a second embodiment of a pouring tube according to the invention; and
• FIG. 6 is a cross-sectional view of the tube shown in FIG. 5.

In these figures, the same reference signs designate identical or analogous elements.

As illustrated in FIG. 1, a pouring tube 1 is formed of a tubular element 2 having an internal central channel 3 of constant section and of an attached plate 4 of rectangular section.

The tubular element 2 is generally made of a refractory material resistant to erosion.

The body of the tubular element 2 may include an insert 5 of zirconium oxide intended to protect at least part of the external wall of the tube from the combined erosive action of steel and air at the location of the steel level in the mold. The lower end of the tubular element 2 has lateral orifices 6, 7 which open in the direction of movement of the tube in a diametrically opposite manner. These orifices are intended to deflect the pouring jet and attenuate the erosive action of the eddies. (Fig. 1)

The upper end of the tubular element 2 carries a perfectly flat upper face forming an integral part of the tubular element 2. The edge of the upper face and its junction with the upper end of the tubular element 2 of the tube are reinforced. by a collar 9 having on the side portions of walls directed in the direction of movement of the tube 1, an excess thickness of ceramic material, so as to have an oblong section. (Fig. 4)

The upper end of the tubular element has the same composition as the tubular element 2 and forms therewith the same single piece or entity. It can have either a simple interlocking surface (Fig. 1 and 3) or a flat surface (Fig. 5 and 6). The first form is suitable for receiving an added plate 4. The upper face of the plate is strictly flat to ensure the tightness of the tube 1 against the sliding plane of the plate. reference not shown, so as to avoid any aspiration of ambient atmospheric air. This makes it possible to prevent the formation of various oxides and bubbles in the mass of metal, considerably reducing the quality of the final product.

The present invention proposes to reinforce the thickness of the pouring tube only in the most stressed places, in the front and rear wall portions of the collar 9. The collar 9 is preferably conical and has an oblong section.

The collar 9 and at least the upper part of the tubular element 2 are optionally covered by a metal protective casing 10. This metal casing 10 follows the shape of the collar 9. It advantageously covers the relatively hard free lateral edges of the upper part of the tube. These lateral flanges serve as a sliding shoe for the pouring tube in the feeding and tube changing device. Without the presence of the envelope, the side edges, due to the hardness of the ceramic material, would scratch the guide rails and cause early wear.

The method of assembling the added plate 4 on the fixing flange 8 does not involve any anchoring part. The fixing flange 8 and the added plate 4 are simply enclosed in a protective metal housing 11.

The collar 9 preferably has a conical shape. As illustrated in Figures 1 and 6, the collar 9 is flush with the front and rear edges of the upper face diametrically opposed by relative to the direction of movement of the pouring tube, when changing the tube.

The lateral edges of the added plate are not affected by these extra thicknesses and can bear on the feeding and tube changing device, in particular on guide rails arranged in the vicinity of a pouring tube and intended to bring a tube from a vertical standby position next to a tube in the casting position, towards said casting position.

Claims (4)

1. Casting tube comprising a tubular element (2) having at an upper end a perfectly flat upper face intended to slide in a device for feeding and changing the tube or a regulating device along the fixed lower face of a reference or movable refractory plate of a valve plate, the assembly of the upper end of the tube (1) being reinforced by a collar (9) and by a protective metallic covering (10), characterized in that the tube has at the level of the collar an over-thickness of ceramic material in relation to the material thickness in the vicinity of another transverse section of the tubular element, and in that the collar of the tube has at the same time a conical shape and an oblong transverse section.
2. Casting tube according to Claim 1, characterized in that the casting tube has at the level of the collar (9), in the wall portions facing in the direction of displacement of the tube, an over-thickness of ceramic material in relation to the material thickness at the level of a lateral wall portion of the tubular element.
3. Casting tube according to Claim 1 or 2, characterized in that the collar (9) is flush with the front and rear edges of the upper face, and in that it is set back from the lateral edges of the attached plate which are intended to bear on the device for feeding and changing the tube.
4. Casting tube according to any one of the preceding claims, characterized in that the collar (9) has on the same side as the diametrically opposed wall portions, in the direction of displacement of the tube, over-thicknesses which reinforce the fixing of a tubular element (2) to a fixing flange (8) of refractory material.

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