DEVICE TO INTENSIFY THE MAGNETIC FIELD IN AN INGOT MOULD

Abstract: Device to intensify the magnetic field in an ingot mould, the device cooperating with an ingot mould body (10) and with a means (11) which is positioned outside an outer jacket (14) of the ingot mould body (10) and generates a magnetic field, whereby independent, replaceable auxiliary extension pole pieces (18) stretching substantially towards a crystallizer (12) are comprised within outer jacket (14) of the mould body (10) in correlation with pole pieces (16).

Description: This invention concerns a device to intensify the magnetic field in a continuous casting ingot mould. To be more exact, the invention concerns a device suitable to intensify the action of the magnetic field generated by a means which generates an electromagnetic field and is located outside an ingot mould. At the present time the means which generate an electromagnetic field are fitted either in the immediate vicinity of the crystallizer or outside the ingot mould itself. Many advantages are obtained by fitting outside the ingot mould the means which generate the electromagnetic field. Among these advantages are the ability to replace the crystallizer easily and to vary its size and also the ability to carry out the replacement of the ingot mould too without having to take action on the means that generate the electromagnetic field or on the means or equipment connected to such generating means. For these reasons many users and producers prefer to employ a means to generate the electromagnetic field which is located outside the ingot mould since the advantages accruing from such an embodiment are often greater than the drawbacks linked to a resulting attenuation of the magnetic field in the crystallizer. Document FR-A-2 315 344 discloses a device for generating an electromagnetic field around a continuous casting ingot mould, the device comprising a ferromagnetic core having extension pole pieces and coils suitable for generating an electromagnetic field which are assembled inside the external jacket of the ingot mould. The present applicant has therefore tackled the problem of obtaining a device suitable to intensify the magnetic field reaching the inside of the crystallizer without thereby changing the position of the means that generates the electromagnetic field, such means thus remaining outside the ingot mould. This is obtained by a device having the features disclosed in claim 1. Dependent claims outline advantageous forms of embodiment of the invention. According to the invention the means that generates the electromagnetic field remains the same as before and is not displaced from its position outside the ingot mould. However, auxiliary extension pole pieces cooperating with the main pole pieces of the coils of the means that generates the electromagnetic field are provided within the ingot mould either as elements which can be inserted or as elements which can be connected to the cooling fluid conveyor surrounding the crystallizer or else as elements which can be connected to the outer jacket of the ingot mould. Such auxiliary extension pole pieces displace substantially the start of the massive dispersion of the magnetic field to the neighbourhood of the crystallizer and thus enable that field to be little attenuated at the time when it enters into cooperation with the crystallizer itself. As we said above, the auxiliary extension pieces may be connected to the cooling fluid conveyor or to the outer jacket or may pass through the cooling fluid conveyor until they are in the immediate vicinity of the crystallizer, or else they may be inserted in appropriate supports provided between the conveyor and the outer jacket. In this way it becomes very easy to replace the crystallizer, possibly in conjunction with the replacement of the cooling fluid conveyor and, when necessary, of the outer jacket too. Such replacement may be fully prepared separately, so that the simple removal of old equipment and the fitting of new equipment take little time and do not entail loss of output or an excessive waste of time. The attached figure, which is given as a non-restrictive example, shows a three-dimensional view in which the upper part of an ingot mould has been cut away so as to show the cooperation of the invention with the mould itself. In the figure an ingot mould body 10 comprises a crystallizer 12 surrounded by a cooling fluid conveyor 13 and externally by an outer jacket 14. Fluid able to move at a high speed is fed between the conveyor 13 and the crystallizer 12, while the outer jacket 14 performs the tasks of feeding, conveying and recovering the cooling fluid. A means 11 which generates an electromagnetic field comprises a ferromagnetic core 17 cooperating with pole pieces 16, about which are positioned coils 15 that generate the electromagnetic field. The pole pieces 16 connect the ferromagnetic core 17 to the outer jacket 14 substantially. The means that generates an electromagnetic field 11 is located outside the ingot mould 10 and the pole pieces 16 of that means 11 cooperate with the outer jacket 14 and, in particular, with the outer wall of the outer jacket 14; the pole pieces 16 may be supported on that outer wall 14 or may reach the neighbourhood of that outer wall 14. According to the invention auxiliary extension pole pieces 18 are provided between the outer jacket 14 and the cooling fluid conveyor 13 and are located in direct correlation with the pole pieces 16. The auxiliary extension pole pieces 18 may be supported substantially on the cooling fluid conveyor 13 or may surmount that conveyor 13 and reach the immediate neighbourhood of the crystallizer 12. The auxiliary extension pole pieces 18 may be rested on the inner wall of the outer jacket 14 and on the outer wall of the fluid conveyor 13 respectively. They may also be supported on one or the other of those walls. According to a variant the auxiliary extension pieces 18 are connected firmly either to the conveyor 13 or to the outer jacket 14 or to both 13-14. According to a further variant the auxiliary extension pole pieces 18 are inserted in appropriate seatings included in the wall of the cooling fluid conveyor 13 or in the outer jacket 14, so that they can be inserted, removed and replaced very easily. According to another variant the auxiliary extension pole pieces 18 pass through the wall of the conveyor 13 and reach the neighbourhood of the crystallizer 12. In the embodiment according to the invention the replacement of the crystallizer 12, or of the crystallizer 12 and conveyor 13, or else of the whole ingot mould 10 will not entail any difficulty and can be carried out in a very short time without thereby causing any waste of time, working problems or even a waste of energy.

Claims: Device to intensify the magnetic field acting on an ingot mould (10) which comprises within an outer jacket (14) a crystallizer (12) surrounded by a fluid conveyor (13), a cooling fluid being able to run through the space between the crystallizer (12) and the fluid conveyor (13), the device including a ferromagnetic core (17) having a plurality of pole pieces (16) about which are fitted coils (15) that generate an electromegnetic field, the device being characterized in that the ferromagnetic core (17), the pole pieces (16) and the coils (15) are installed outside the outer jacket (14), and in that auxiliary extension pole Pieces (18) are included within the outer jacket (14) and cooperate with the pole pieces (16) and extend towards the crystallizer (12). Device as claimed in Claim 1, in which the auxiliary extension pole pieces (18) extend from the inner wall of the outer jacket (14) to the outer wall of a cooling fluid conveyor (13) and are substantially in contact with at least one of such walls. Device as claimed in Claim 1 or 2, in which the auxiliary extension pole pieces (18) pass through the wall of the fluid conveyor (13) and face the inner surface of that conveyor (13). Device as claimed in any claim hereinbefore, in which the auxiliary extension pole pieces (18) are supported on the inner wall of the outer jacket (14). Device as claimed in any claim hereinbefore, in which the auxiliary extension pole pieces (18) are supported on the wall of the cooling fluid conveyor (13).

Inventors: CIANI, LORENZO
Applicants: CEDA S.P.A. COSTRUZIONI ELETTROMECCANICHE E DISPOSITIVI D'AUTOMAZIONE, DANIELI & C. OFFICINE MECCANICHE S.P.A.
Application year: 1988
Main classification: B22D11
IPC codes: B22D11