Dispensing – Molten metal dispensing – Flow controllers or assists
Reexamination Certificate
2002-10-16
2004-08-10
Kastler, Scott (Department: 1742)
Dispensing
Molten metal dispensing
Flow controllers or assists
C222S606000, C164S437000
Reexamination Certificate
active
06772922
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a particular inner nozzle adapted to be used with a clamping device for an inner nozzle of a metallurgical vessel and to this new device.
BACKGROUND OF THE INVENTION
It is known that continuous casting of a liquid metal is generally carried out by means of an installation comprising various refractory components forming a channel between two successive metallurgical vessels. These components perform various functions, namely conveyance of the liquid metal, protection of the liquid metal against cooling and chemical attack from the surrounding atmosphere and, where appropriate, regulation of the pouring flow-rate of the liquid metal. These components may be, for example, an inner nozzle generally supported on a well block integral with the bottom of the upper metallurgical vessel, a submerged entry nozzle or a pouring shroud, a collector nozzle, or the fixed or mobile plates of a slide valve.
In recent years, considerable effort has been deployed in an attempt to achieve maximum simplicity of the various refractory components forming the pouring channel. Thus, with a view to reducing the number of joint surfaces between refractory components (all of which are points of potential air ingress), increasingly frequent use has for example been made of pre-assembled components or components formed from a single block, constituting the inner nozzle and the fixed upper plate located just below the inner nozzle and against which is placed either the mobile plate of a slide valve or the plate of a replaceable submerged entry nozzle (which may form an assembly with the submerged entry nozzle or forming a one-piece component with the latter). Such one-piece components are described for example in international patent application WO 88/06500.
Various devices are known which make it possible either to regulate the pouring flowrate, or to introduce and replace the submerged entry nozzle without having to interrupt the casting operation, or even to combine these two operations. These devices can be divided into two categories: a first type wherein the fixed upper plate (whether or not forming a one-piece assembly with the inner nozzle) is pushed upward and retained in position by a device acting on its upper face (see for example U.S. Pat. No. 4,573,616). In general, the upward thrust is transmitted by the refractory components located downstream (mobile plate of a slide valve or plate of a submerged entry nozzle) which are themselves pushed upward, directly or otherwise, by various spring mechanisms. According to a second type of device, the fixed upper plate is pushed downward and retained in position by a fixed stop against which the lower surface of the fixed upper plate bears (see for example international patent application WO 91/03339). This fixed stop thus defines in an extremely precise manner a reference plane in which slides the mobile refractory component situated immediately downstream of the fixed upper plate (mobile plate of a slide valve or plate associated with a submerged entry nozzle). It is known that it is necessary to make a perfectly airtight connection between the different refractory components constituting the pouring channel; therefore, it is important that the pressure with which the lower components are pushed towards the fixed upper plate is constant and is capable of being defined with great precision. Given that the upward thrust on these components is realised by means of a spring-operated device, the relative height of these components is a parameter that can considerably influence the pressure. In devices of the first type, the dimensions of all the refractory components involved are very closely toleranced so that their relative height in the stacked assembly formed by them is precisely defined. In the second type of device, the dimensional tolerances, particularly of the fixed upper plate, no longer have any influence on the pressure exerted between the various refractory components because the reference plane against which the components located downstream bear is defined independently of the said plate. Consequently, this second type of device can theoretically accommodate fixed upper plates (whether or not forming a one-piece assembly with the inner nozzle) having substantially less strict and therefore less onerous dimensional tolerances.
In practice, however, mechanical solutions allowing the fixed upper plate to be pushed downward (against the fixed stop holding it in position) are not wholly compatible with the use of plates presenting unduly large dimensional irregularities. In particular, even if a certain tolerance can be accepted on the thickness, it is necessary for the upper surface of the fixed upper plate to be perfectly flat and parallel to the lower surface. One of the objects of the present invention is therefore to provide a clamping device for the fixed upper plate (whether or not forming a one-piece assembly with the inner nozzle) which accommodates fixed upper plates with wide dimensional tolerances.
Where use is made of a one-piece inner nozzle, it may also be no easy matter to dismantle the mechanisms referred to above when the pouring sequence is completed and when it is necessary to undertake dismantling to facilitate maintenance operations on the said mechanisms or to replace worn refractory components or to recondition the upper metallurgical vessel for the next sequence in which it will be engaged. In effect, a situation can arise at the end of the sequence in which liquid metal solidifies in the inner nozzle and binds the latter to the bottom of the upper metallurgical vessel. In the case of a fixed upper plate/inner nozzle assembly, this does not pose any real problem as all that is required is to separate these two components in order to remove the mechanism leaving the inner nozzle full in the bottom wall of the upper metallurgical vessel. With a one-piece inner nozzle, this is no longer possible because, as indicated above, the fixed upper plate is either held at the top (devices of the first type) or pushed downward (devices of the second type). In both cases, the presence of a device acting on the upper surface of the fixed plate prevents disengagement of the mechanism addition, the limited available space considerably impedes, or even prevents, operations to disassemble the retaining or downward-pushing device of the fixed upper plate.
SUMMARY OF THE INVENTION
The object of the present invention is precisely a novel clamping device for the inner nozzle wherein the latter is held securely and precisely in place in the well block, but which however allows simple and rapid disassembly of the clamping device. By virtue of this novel device, the flow regulation or tube-changing mechanism or the mechanism performing these two operations can very easily be detached from the tundish.
According to the invention, the clamping device includes at least two assemblies each composed of a clamp pivoting about an horizontal axis and fitted with a groove receiving a shoe generally cylindrical in shape incorporating a flat surface parallel to the axis of said cylinder, said shoe being capable of pivoting in the groove. The shoe is therefore arranged sliding or sliding just in the groove of the clamp.
By virtue of the presence of the pivoting shoe, the contact between the clamp and the surface of the inner nozzle bearing on said clamp is established automatically and without operator intervention with the flat of the shoe oriented in a plane parallel to an upper surface of the plate of the inner nozzle. This results in substantially improved clamping of the nozzle without generating large local stresses at the inner nozzle. It will also been noted that the clamping system according to the present invention is composed of several assemblies (clamp/shoe) which are totally independent of each other so that the clamping device is suitable for inner nozzles with very wide tolerances, and even where the dimensions (thickness) vary from one side to the other of its tubular section.
Preferab
Boisdequin Vincent
Collura Mariano
Lattuca Calogero
Renard Jean-Luc
Kastler Scott
Klemz, Jr. Robert S.
Vesuvius Crucible Company
Williams James R.
LandOfFree
One-piece inner nozzle and clamping device for holding such... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with One-piece inner nozzle and clamping device for holding such..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and One-piece inner nozzle and clamping device for holding such... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3276613