GB2135919A

GB2135919A - Improvements in horizontal continuous casting

Info

Publication number: GB2135919A
Application number: GB08404374A
Authority: GB
Inventors: Frank Martiny
Original assignee: Mannesmann AG
Current assignee: Vodafone GmbH
Priority date: 1983-02-23
Filing date: 1984-02-20
Publication date: 1984-09-12
Also published as: GB2135919B; JPS59159251A; FR2541148B1; SE8306859D0; DE3306186A1; DE3306186C2; SE8306859L; FR2541148A1; GB8404374D0

Abstract

In order to join a starting head (9) to a cast strand, a cavity (13) is formed for the head by discs (8) connected to meltable plates (11) sealing an inlet for molten metal into the cavity. The head (9) has projecting arms (9a) which assist in forming connection with the strand. A probe (16) detects filling of the cavity (13) so that withdrawal of the head (9) from the mould (1) may then commence. <IMAGE>

Description

SPECIFICATION Improvements in continuous casting It is known to establish a tensile connection between a drawing machine and the leading end of a continuously cast strand by casting-on to the strand a so-called starting head connected to a rod to which tension is applied. The starting procedure can therefore be repeated using the apparatus during each successive casting operation.

The prior art includes process and an apparatus for this purpose in horizontal continuous casting whereby the feed nozzle of the casting container is sealed relative to the mould by insertion of a stopper Melt is subsequently poured into the container and the stopper melts only after the slag particles in the melt have risen and left the region of the feed nozzle. This method avoids disorders in the cast skin of the strand caused by inclusion of slag or other heat-resistant particles during the starting procedure.

The known process meets the requirement of completely emptying and drying the supply vessel and the horizontal continuous casting mould on its internal surfaces. However, it has been found that the cooling of the liquid metal flowing round the starting head can be further accelerated and that it is necessary to provide a more reliable connection between the solidifying molten metal and the starting head.

The present proposal therefore seeks to improve cooling and simultaneous formation of the necessary connection between the starting head and the cooling molten metal, in which simple drawing of the starting head from the horizontal continuous casting mould is ensured.

To this end, after a preheating operation, the supply vessel is sealed by a sealing element and the horizontal continuous casting mould is sealed with simultaneous formation of a starting head cavity inside the horizontal continuous casting mould. The removal of the cast strand is initiated after a predetermined time interval depending upon the quantity of liquid in the starting head cavity. In this process, the molten metal flows progressively round the starting head and simultaneously wets the internal mould wall so that solidification of the external regions can immediately be effected by cooling of the mould. This advantageously leads to immediate release of the solidifying cast material from the internal mould wall. An advantage of the process lies in the very accurate determination of the time for introduction during the removal of the cast strand.To sum up, the cast strand can therefore be removed more simply and without complications from the mould.

The molten metal may be fed into the starting head cavity only when the bath level in the supply vessel is located at least above the level of the inlet opening of the mould. This measure which can be controlled using a sealing element of the supply vessel ensures that an adequate quantity of melt is available to fill the cavity very rapidly and surround the starting head.

Apparatus for carrying out the process is designed in such a way that a sealing body for the mould separates a cavity and is connected to a starting head having at least one arm which extends from the interior outwards at an inclination to the radial plane with a clearance relative to the internal mould wall.

This starting head has the advantage that it does not touch the internal mould wall and causes no complications during drawing from the mould. The starting head also creates an extremely secure connection between the cast strand and the starting rod.

The sealing body, the starting head and at least one sealing element for the feed opening in the furnace brick may be joined together. In addition to the accurate spacing between the sealing body and the sealing element for the furnace brick, a reliable seal of the furnace brick by means of one or more sealing elements is advantageous.

This measure also permits the sealing element for the feed opening in the furnace brick to be composed of one or more metal plates which are arranged one behind the other and can be melted on. Aluminium is particularly suitable for such metal plates in view of the casting of various steels. With these several metal plates arranged one behind the other, the time for the melting on and therefore for the filling of the cavity can be adjusted quite accurately.

The time for filling of the cavity may be determined more accurately or monitored accordingly.

For this purpose, it is proposed that a sensor be provided in the cavity for determining the level of the melt, supply lines from the sensor running inside the cross-section of the starting rod and being connected to measuring, control and/or monitoring circuits.

The electrical switching conditions of these measuring, control and/or monitoring circuits can be influenced since the sensor may consist of two measuring poles which can be electrically connected by the melt.

The drawing shows an axial section through a horizontal continuous casting mould just upstream of the starting phase during the horizontal continuous casting of steel or steel alloys.

Referring to the drawing, a horizontal continuous casting mould 1 is connected with a supply vessel 2 by way of an insulator 3, an intermediate ring 4 and the wear-resistant sealing ring 5.

The molten metal, for example steel, with a superheat addition relative to the melt temperature, flows continuously during the second casting operation into the supply vessel 2 and thence through the inlet opening 6 into the horizontal continuous casting mould 1 and is removed therefrom in an externally solidified form as cast strand or billet.

The strand is started by forming a connection with a starting rod 7 to enable the drawing forces to be transmitted to the cast strand.

In a first phase, the mould 1 is heated internally and/or externally. In a subsequent second phase, the supply vessel 2 and the mould 1 are sealed simuitaneously using sealing body 8 formed from graphite discs 8a connected to the starting rod 7 and having a diameter somewhat greater than that of the rod. The starting rod 7 is connected by a fixing element 15 to a starting head 9 from which extends a metal rod 10 bearing cast-on metal plates lie serving as a sealing element 11. The metal plates 1 1a serve to delay and thereby regulate the penetration of the molten metal into the horizontal continuous casting mould both according to time and quantity.

The number of plates and the temperature at which they melt are selected accordingly. The inlet opening 2a of the furnace brick 2b is automatically sealed during the insertion of the starting rod 7, head 9, rod 10 and plates 11a. During the insertion operation, only the graphite discs 8a slide on the internal mould wall 1 1 a. This slight contact is sufficiently insignificant to avoid any possible damage to the internal mould wall la. The starting rod 7, on the other hand, is inserted into the interior of the mould 1 with clearance, maintaining an air gap 12.

The head 9 is arranged in a cavity 13 whose volume is calculated together with the preceding spaces and is therefore known so that the time for the filling of the cavity 13 is also determined.

Extending radially and diagonally outwards from the head are a number of arms 9a which define a clearance 14 relative to the internal mould wall la are fixed in the head 9.

To determine the time at which pouring of the molten metal inside the cavity 13 is completed, there is provided measuring, control and/or monitoring circuit including the sensor 16, the leads 16a and 16b from which poles run through the duct 17 formed by a groove 17a in the mould wall 1a and by the groove 17b in the starting rod 7. The duct 17 is dimensioned in such a way that air which is displaced through the molten metal in the cavity 13 can escape to the atmosphere. The leads 16a and 16b are connected to a power source 18, a signal device 19, for example a pilot light, being arranged in one of the leads. As soon as the poles 20 are electrically coupled by the molten metal entering the cavity, the signal device 19 indicated the end of the filling operation so that the drawing operation can be initiated using the starting rod 7 and a drawing machine not shown in detail.

Claims

1. A process for the casting-on during the horizontal continuous casting of metals, in particular of steel, in which the mould is preheated and subsequently the supply vessel is filled, wherein after the preheating operation, the supply vessel is sealed by a sealing element and the mould is sealed and a starting head cavity simultaneously formed inside the mould, the removal of the cast strand being initiated after a given time period as a function of a predetermined level in the starting head cavity.

2. A process according to claim 1, characterised in that the metal is fed into the cavity intended for the starting head only when the bath level in the supply vessel is located at least above the level of the inlet opening of the mould.

3. An appararus for carrying out the process according to claims 1 and 2, characterised in that a sealing body for the horizontal continous casting mould separates a cavity and is connected to a starting head having at least one arm which extends from the interior outwards at an inclination to the radial plane and ends with a clearance relative to the internal mould wall.

4. An apparatus according to claim 3, characterised in that the sealing body, the starting head and at least one sealing element forthe feed opening in the furnace brick are joined together.

5. An apparatus according to claim 4, characterised in that the sealing element for the feed opening in the furnace brick consists of one or more metal plates which are arranged one behind the other and can be melted on.

6. An apparatus according to claims 3 to 5, characterised in that in the cavity there is provided a sensor for determining the melt fullness level, whose leads run inside the cross-section of the starting rod and are connected to measuring, control and/or monitoring circuits.

7. An apparatus according to claim 6, characterised in that the sensor consists of two measuring poles which can be electrically connected via the melt.

8. Apparatus substantially as herein described and illustrated.