Metal founding – Process – Shaping liquid metal against a forming surface
Patent
1991-09-10
1993-03-30
Batten, Jr., J. Reed
Metal founding
Process
Shaping liquid metal against a forming surface
164137, 164306, 164339, 164342, B22D 1804
Patent
active
051975300
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for pressure casting flat metal products, such as slabs, from a ladle of molten metal.
In a manner known per se, the molten metal contained in this ladle is cast, by means of the pressure of compressed air, into a mould comprising two lateral walls equipped with graphite blocks and spacers delimiting a cavity for receiving the molten metal and two half-shells which are open towards the top and towards the bottom, which are complementary and placed above a shaft. The latter is delimited by a front spacer, that is to say located on the side via which the molten metal penetrates into the mould, and by an end of an upper spacer and forms an access for the molten metal to the inside of the hollow volume of the half-shells in order to form therein a header of molten metal.
In pressure casting, the header plays an important role insofar as it participates, to a large extent, in the result, that is to say in the quality of the slab. The role of this header is essentially to form a reservoir of molten steel which refeeds the slab during shrinkage and cooling thereof between the graphite blocks and the spacers. The header forms a mass of steel which is sufficient, after the end of the cast and the solidification of the bath, to control the virtually inevitable shrinkage connected with casts in moulds, in order that this should not affect the final product.
Another function of the header is to leave contraction of the slab free, during cooling, in order to avoid the cracks which inevitably appear when blocking is too rigid. To this end, the mould of the header consists of the abovementioned two half-shells, generally made from cast iron, which are pressed, on the one hand, on the front spacer and, on the other hand, on the upper spacer through the action of elastic clamping members placed on each side of the half-shells.
The force of application of the half-shells on the spacers must be much greater than the ferrostatic force in order to guarantee no leakage of the molten metal. However, this force, which is essential to combat the infiltrations of steel which would arise in the event of poor clamping, opposes the free shrinkage of the molten steel in the header via the base of the shaft towards the actual slab and this opposition is detrimental to the quality of the slab obtained. In fact, the clamping force exerted by the elastic members on the half-shells interferes with the shrinkage of the slab via the base of the shaft towards the cavity contained between the graphite blocks. Thus, if the clamping force of the half-shells is greater than the force of which the skin of the molten metal during solidification is capable, major cracks inevitably appear at the transition between the actual slab and the header.
The invention aims to propose a method and a device for implementing the latter which eliminate the abovementioned drawbacks.
According to the invention, the pressure-casting method is characterized in that, during the cast of the molten metal in the half-shells and the start of its solidification, a high clamping force of the half-shells is maintained and then, when the surface skin of the header is sufficiently solidified, the clamping force is reduced in order to eliminate any resistance to the contraction of the flat product.
Under these conditions, the walls of the half-shells offer less resistance to the shrinkage of the slab after reduction of the clamping force. Thus, virtually no further notable cracking is observed at the slab/header transition.
According to the invention, the device for implementing this method comprises, on each side of the half-shells, means for substantially reducing the clamping force of the elastic members after the cast and at the beginning of the solidification of the molten metal.
According to one embodiment of the device, the abovementioned means comprise, for each half-shell, a jack articulated on the latter and carried by a fixed part of the mould so that it is possible to exert, on the associated half-shell, a transverse traction
REFERENCES:
patent: 3163887 (1965-01-01), Schultz
patent: 3459256 (1969-08-01), Jeffreys
patent: 3590904 (1971-07-01), Woodburn, Jr.
patent: 3701377 (1972-10-01), Fisher
patent: 4733714 (1988-03-01), Smith
Corubier Michel F.
Vatant Robert A.
Batten, Jr. J. Reed
Cruesot-Loire Industrie and Clecim
LandOfFree
Method and apparatus for pressure casting flat metal products does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for pressure casting flat metal products, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for pressure casting flat metal products will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1275113