GB2299045A

GB2299045A - Joining ceramic moldings

Info

Publication number: GB2299045A
Application number: GB9605397A
Authority: GB
Inventors: Manfred Slamenik
Original assignee: Veitsch Radex GmbH and Co OG
Current assignee: Veitsch Radex GmbH and Co OG
Priority date: 1995-03-18
Filing date: 1996-03-14
Publication date: 1996-09-25
Anticipated expiration: 2016-03-14
Also published as: FR2731636A1; GB9605397D0; IT1283243B1; GB2299045B; ITMI960491A1; BE1010995A3; ITMI960491A0; DE19509969C1

Description

1 Positive-locking Connection of Ceramic Moldings S p e c i f i c a t i o

n 2299045 The present invention pertains to a positive-locking connection between adjacent surface sections of two ceramic moldings. Both the state of the art and the present invention will be represented below on the basis of a shroud (pouring spout), which consists of a basic tube and a tubular bumper, which is pushed over the discharge-side end of the basic tube and is connected to the basic tube. However, the present invention is not limited to this application. The positivelocking connection can also be effected between any other moldings which are tc be fitted together along adjacent surface sections.

A pouring spout of the above-described type is arranged between a ladle and a pouring distributor (tundish) and is to prevent the oxidation and the cooling of the metal melt being passed through the spout.

The said bumper is used to protect the discharge-side end of the basic tube and thus to prolong the life of the pouring spout. The pouring spout is subject to a high thermal shock 2 stress in the range of in.miersion. Expansions/contractions can be better compensated by the two-part design.

As is apparent from DE 93 18 726 U1, the fastening of the tubular bumper, which is also called a sleeve, represents a considerable problem. The following are some of the requirements imposed on the connection:

good resistance to thermal shocks, tightness in the area of the connection, absolute concentricity of the basic tube and the bumpel' (sleeve).

Connection by means of a refractory adhesive as well as the bonding in of tongues in the outer metal jacket of the basic tube are described as prior-art suggested solutions in DE 93 18 726 U1, and it is pointed out at the same time that these suggested solutions do not eliminate the risk of separation of the sleeve from the basic tube during the handling of the latter.

The said registered utility patent therefore suggests that a perforated and/or corrugated metallic reinforcement, which is attached to an outer metal jacket of the tube, be embedded into the refractory material of the sleeve.

The ceramic connection is consequently replaced with a metallic connection.

The prior-art suggested solution requires a considerable design effort, because both parts must be provided with metal jackets. At the same time, there is a risk of oxidation of the metallic reinforcement, which leads to cracks due to expansion as a consequence of the increase in volume.

3 Thus, the basic object of the present invention is to improve a positive- locking connection of the above-described class while the above-mentioned three criteria are taken into account.

In its most general embodiment, the present invention suggests for this purpose a positive-locking connection between adjacent surface sections of two ceramic moldings which are provided - along their opposite surface sections with bead-like depressions which are located opposite each other in pairs in the assembled state of the moldings and are filled with a mortar which can be introduced to at least one of the said depressions via at least one feed line.

In other words, a kind of "in situ" anchor is created with the said mortar between adjacent refractory ceramic moldings.

The moldings are provided for this purpose with the said bead-like depressions, are brought into the desired position in relation to one another, and the mortar is subsequently introduced via the feed line into the bead-like depressions, where it creates a kind of "bridge" or "anchor" between the two parts after setting.

The term mortar represents all types of masses which can be introduced in the viscous (pasty) form via the said feed lines into the bead-like depressions and set there and have, in the set state, a temperature stability that is above the maximum temperature occurring during the industrial use of the said moldings. If the corresponding surface sections of the moldings to be connected extend concentrically to one another, 4 it is also possible to arrange the bead-like depressions at least along one molding circumferentially (annularly), especially because a single feed line is sufficient for the mortar in this case. At the same time, a type of circumferential seal is created between the adjacent refractory moldings after the filling of the corresponding bead-like depressions.

The depressions in the refractory moldings as well as the transition area of the depressions to the adjacent surface sections shall be rounded according to one embodiment in order to rule out notch effects during the use of the moldings as much as possible.

Depressions in the form of a groove (annular groove) with semicircular cross section and rounded transition into the adjacent surface sections have proved to be particularly advantageous for the connection of concentric moldings in preliminary experiments.

In an advantageous variant, the present invention suggests that the surface of at least one depression (the depressions of one molding) be coated with a separating means. A continuous (ceramic) bonding (connection) between the adjacent moldings is thus prevented, which has a favorable effect, especially on the resistance to thermal shocks, without appreciably compromising the sealing of the connection at the joint point. The adjacent surface sections of at least one molding may also be correspondingly coated with a separating means, so that there is no material-locking connection between the moldings in the assembled state.

The separating means may consist of, e.g., a foil, but it is also possible to provide the corresponding depression or the corresponding surface sections with a refractory lacquer, an engobe, or another refractory separation layer.

As was described, one especially advantageous application is the connection of the moldings of a shroud, which consists of a basic tube and a bumper (a sleeve), which is pushed over the basic tube and is connected to same in the above-described manner.

Contrary to DE 93 18 726 U1, metallic reinforcements or purely metallic compounds are avoided. The said depressions, which may be designed as "discrete" (individual) depressions or as channel-like depressions, can be formed directly during the pouring or pressing of the moldings. However, it is also possible prepare the said depressions by mechanical aftertreatment after the preparation of the moldings. In either case, only minor additional steps are necessary.

Additional features of the present invention arise from the features of the subclaims as well as the other application documents. These also include the following description of the figures, which thus also contains general features.

In schematic representations, Figure 1 shows a shroud, comprising a basic tube and a corresponding bumper in a sectional view after shaping, Figure 2 shows the view according to Figure 1 after preliminary assembly, and Figure 3 shows the components according to Figure 1 in the assembled state.

Figure 1 shows a shroud, which comprises a basic tube 10, 6 the lower part of which is shown, and a tubular bumper 12, wherein the two parts 10, 12 consist of a refractory ceramic material.

Bead-like depressions 14a, 14b, each with semicircular cross section, are shaped on the outer circumferential surface of the discharge end of the tube 10 during the shaping.

The bumper 12 comprises a sleeve, which has a step-like recess 16 in its upper section facing the tube 10, wherein the internal diameter of the lower section 12u corresponds to the internal diameter of the tube 10, and the internal diameter of the upper section 12o is slightly larger than the external diameter of the tube 10 in the corresponding discharge-side end.

Oace of the upper section loo is provided The inner sur:

with circumferential depressions, which have a semicircular cross section and are arranged such that the depressions 14a, 18a and 14b, 18b are located directly opposite each other in the assembled state of the tube 10 with the sleeve 12 (Figure 3), while at the same time the front-side end loe of the tube 10 is in contact with the corresponding step 16s of the recess 16 (Figure 3).

Furthermore, the outer circumferential surface of the tube 10 is flatly in contact with the inner side of the upper section 120 of the sleeve 12 in the assembled state (Figure 3).

The bead-like annular groove 18a is connected to the annular groove 18b by an additional groove 18c extending vertically (in the direction of the central longitudinal axis 1 7 M of the sleeve 12) on the inner side of the upper section 12o of the sleeve 12, which continues below the annular groove 18b and passes over - in the lower part 12u of the sleeve 12 into a channel-like section 18d, which extends after an involution to the outer circumferential surface of the sleeve 12 with a section 18e.

The annular grooves 18a, b as well as the grooves/channels 18c, d and e are molded during the shaping of the sleeve 12. In the case of the channel-like sections 18d, 18e, this is done by introducing a material which was destroyed during the firing of the sleeve 12 while exposing the channels 18d, 18e.

In a next step (Figure 2), a metal foil 20, which extends from a section somewhat above the annular groove 14a to the front-side end loe and around this [end], was circumferentially applied to the discharge-side end of the tube 10.

Figure 3 shows the assembled state of the tube 10 and the sleeve 12. To prepare the positive-locking connection of the moldings 10, 12, a pasty mortar is now pressed into the annular depressions 14a, 18a, 14b, 18b via the channels 18e, 18d as well as the groove-like depression 18c, and the said mortar subsequently has a circular cross section in the area of the corresponding grooves 14a, 18a; 14b, 18b. The mortar subsequently sets and thus creates a positive-locking connection between the tube 10 and the sleeve 12 of the shroud. The foil 20 prevents a material-locking connection, i.e., a ceramic bonding, from forming between the components 8 10, 12. This is advantageous because the resistance to thermal shocks of the shroud can be markedly improved due to the physical separation of the two components 10, 12 thus ensured.

According to a variant, the tube is not provided with two circumferential annular grooves 14a, 14b, but with six slotlike grooves, wherein three each extend on the circumference at spaced locations from one another on one line (i.e., aligned with one another). In other words, the annular grooves 14a, 14b are interrupted three times here, so that three discrete depressions are formed, which are located opposite each other in the assembled state. The number of grooves is, of course, freely selectable.

0 c.

9 ;L.AIMS:

Positive-locking connection between adjacent surface sections of two ceramic moldings, which are provided along their mutually opposite surface sections with said bead-like depressions, which are located opposite each other in pairs in the assembled state of the said moldings and are filled with a mortar, which can be introduced to at least one of the said corresponding depressions via at least one feed line.

2. Positive-locking connection in accordance with claim in which the corresponding surface sections of the said moldings to be connected extend concentrically to one another.

3. Positive-locking connection in accordance with claim 2, in which the said depressions have the shape of an annular groove with semicircular cross section.

4. Positive-locking connection in accordance with one of the claims 1 through 3, in which the surface of at least one said depression is coated with a said separating means.

5. Positive-locking connection in accordance with one of the claims 1 through 4, in which at least one surface section of a said molding separating means.

is coated with a said 6. Positive-locking connection in accordance with claim 4 or 5, in which the said separating means, consists of a f oil.

7. Positive-locking connection in accordance with claim 4 or 5, in which the said separating means consists of a refractory lacquer or a ceramic engobe.

io 8. Positive-locking connection in accordance with one of the claims 1 through 7, in which the said depressions in the said ceramic moldings as well as the transition area of the said depressions to the adjacent surface sections are rounded.

9. Positive-locking connection in accordance with one of the claims 1 through 8, in which the said moldings comprise a said basic tube and a said sleeve attached to the said basic tube at its end.