Electromagnetic mold for continuous castings

[54] ELECTROMAGNETIC MOLD FOR CONTINUOUS CASTINGS

[75] Inventor: Laurent Zuber, Chalais, Switzerland

[73] Assignee: Swiss Aluminium Ltd., Chippis, Switzerland

[ * ] Notice: The portion of the term of this patent subsequent to Apr. 23, 2002 has been disclaimed.

[21] Appl. No.: 701,962

[22] Filed: Feb. 14,1985

[30] Foreign Application Priority Data

Feb. 22, 1984 [CH] Switzerland 848/84

[51] Int. a.* B22D 27/02

[52] U.S. CL 164/503; 164/436

[58] Field of Search 164/503, 467, 436, 491;

60/581, 592, 594; 417/383

[56] References Cited

U.S. PATENT DOCUMENTS

2,009,515 7/1935 Pardee 60/592 X

2,399,505 4/1946 Phillips 60/594 X

2,414,675 1/1947 Stelzer 60/594

4,093,184 6/1978 Wieschel 60/592 X

4,512,386 4/1985 Haller 164/503 X

FOREIGN PATENT DOCUMENTS 1469166 2/1967 France 164/436

Primary Examiner—Kuang Y. Lin

Attorney, Agent, or Firm—Bachman & LaPointe

[57] ABSTRACT

An electromagnetic mold for continuous casting comprises side and endwalls each of which features an inductor part with induction loop and a screen. An endwall can be displaced along and secured to the sidewalls by means of releasable bolts while the related inductor parts and the screens are connected to closed loops via a clamping facility with pistons in piston chambers. To improve this means of fixing and for faster fitting into place, the piston chambers are connected via branch lines or channels to a compression chamber in a piston bore and fitted with a compression medium which can be put under pressure by a main piston.

4 Claims, 2 Drawing Sheets

4,892,

ELECTROMAGNETIC MOLD FOR CONTINUOUS
CASTINGS

CROSS REFERENCE TO RELATED 5
APPLICATION

This application is related to co-pending application Ser. No. 441,225, now U.S. Pat. No. 4,512,386, which is assigned to the assignee of the instant application. ^

BACKGROUND OF THE INVENTION

The present invention relates to an electromagnetic mold for continuous casting having side and endwalls each of which comprises an inductor part with inductor loop and a screen such that at least one end wall can be 15 displaced along and secured to the sidewalls by means of releasable bolts, while the related inductor parts and screens are connected to closed loops via a clamping facility with pistons in piston chambers.

Using such electromagnetic molds for direct chill 20 casting the molten metal is poured at a given rate onto a dummy block situated within a loop-shaped electrical inductor. High frequency alternating current in the inductor generates an electromagnetic field which constrains the molten metal horizontally within the indue- 25 tor in a shape which is essentially determined by the inner contours of the inductor loop. By jetting with coolant, for example water, the metal at and close to the surface solidifies rapidly as the strand is lowered.

Such equipment usually features an electromagnetic 30 screen which is tapered downwards. This is mounted coaxially within the inductor and is made of metal (for example stainless steel). The shape of this screen has the effect of diminishing the strength of the magnetic field above the inductor so that the electromagnetic forces 35 limiting the cross-section of the head of the ingot are smaller. A more detailed description of the advantages of such a screen is presented in U.S. Pat. No. 3,605,865.

As do rectangular ingots cast by conventional continuous casting the ingots cast continuously with the above 40 mentioned electromagnetic molds usually exhibit slightly concave sidewalls. The reasons for this disturbing effect are described in detail in the German patent publication No. DE-OS-28 48 808.

Electromagnetic molds for continuous casting are 45 complicated and expensive, especially because of the small dimensional tolerances which have to be observed when making the molds. Also, a large number of ingot formats is normally required, which means that a corresponding number of molds has to be kept in store. It will 50 be readily appreciated that this is economically unattractive.

Known from the German patent No. DE-AS 10 59 626 is a continuous casting mold with displaceable endwalls. The function and construction of a conventional 55 continuous casting mold are, however, basically different from those of an electromagnetic mold; the special knowledge of one cannot therefore be transferred to the other. The conventional mold serves to conduct away the heat of the melt by direct contact with the melt. It 60 also serves as the container for the melt and must therefore be sealed around its whole periphery.

The electromagnetic mold, however, does not come into contact with the melt. It serves to supply the electric current in a specific manner and contains facilities 65 for influencing the magnetic field further.

For this reason special locking elements were developed for electromagnetic molds to permit variable posi

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tioning and fixing of the endwalls on the sidewalls— which makes it possible to vary the size of the mold opening and thus ingot cross-section. A special clamping device on the endwalls connects the relevant inductor parts to the screen so that there are always closed loops with the mold. This clamping device features a camshaft which, when rotated causes pistons to bring special contact elements into contact with each other. This clamping device, however, suffers the disadvantage that it has to be specially actuated for each of the contacts to be made between the end and sidewalls, and such that for uniform setting one requires exactly coordinated, synchronous movements. Furthermore the pressure applied to the contact elements depends solely on the rotation of the camshaft which, if made such that its motion is very easy, introduces the risk of the contact pressure being reduced while the mold is in service. Also the contact elements can be withdrawn from the clamping device only to the same extent as the height of the cam.

Accordingly, it is the principal object of the present invention to develop a clamping device for making the connection between the endwall and sidewalls, which does not exhibit the above noted disadvantages and, in particular, can be brought into use very quickly. Furthermore, the possible range for displacement of the compression piston and its pressure should be variable.

SUMMARY OF THE INVENTION

The foregoing object is achieved by way of the present invention wherein piston chambers are connected, via branch lines or channels, to a compression chamber in a piston bore and are fitted with a compression medium which can be put under pressure by a main piston.

If a pressure is applied to the main piston, this ensures that the pistons in the piston chambers move uniformly and are subjected to a uniform pressure.

The main piston should preferably be fitted, on the side away from the compression chamber, with bellows fitted at one end with a plate against which rests a disc that is penetrated off-center by an axle shaft. If this disc is moved in a particular direction by means of a lever, as a result of the off-center positioning of the shaft, the disc presses on the plate which in turn presses on the bellows and thus also on the main piston. The bellows sever basically as a buffer to cushion excessively high pressure in the compression chamber and/or to even out for example vibrations within the mold. This way the whole clamping facility can as desired be brought into contact with the inductor parts and screen by means of a single move of the hand. The same applies to releasing the clamping facility.

Beyond the main piston the compression chamber in the piston base is delimited by a regulating piston, the position of which can be altered by a setting screw. This enables the pressure of the pistons on the contact elements to be increased and/or larger spacing between the clamping facility and the sidewalls to be accommodated.

All the pistons are effectively sealed against the walls of their piston chambers by means of ring-shaped seals.

This clamping facility is extremely simple in design and therefore very resistant to break down. Any desired pressure medium can be provided in the compression chamber and channels or branch lines, preferably a hydraulic fluid.