Electromagnetic valve means for tapping molten metal

Claim 2

In a furnace of the submerged resistor type having a hearth and one or more channels for the circulation of molten metal between the hearth and channels, where melt in the channel or channels, together with melt in the hearth, forms secondary circuits in which currents may circulate between the hearth and channels induced as a result of transformer action from one or more AC-fed primary coils, an electromagnetic valve for regulating the circulation of molten metal between the hearth and the channels comprising: means for establishing a magnetic flux through the molten metal in the channel, the flux direction being perpendicular to the direction of the channel, whereby a force is produced by cooperation between current in the channel and flux in either direction of the channel in dependence of the direction of current and flux in accordance with Biot-Savart''s law.

Claim 3

A furnace according to claim 1, in which the means is energized with alternating current substantially in phase with the current in the coils, the coils and the means being series-connected.

Claim 4

A furnace according to claim 1 intended to circulate molten metal in the inductor channels of a channel-type induction furnace, the channels consisting of at least two side channels leading from a furnace hearth and at least one bottom channel joining the lower parts of the side channels, characterized in that near the junction between the bottom channel and one side channel or near the bottom channel and a vertical channel leading from the middle of the bottom channel to the hearth, the means is arranged with a flux direction straight across the bottom channel, separated from the ordinary heating circuit and having an ''''air gap'''' ( delta ) in the metal melt, and that the side channel or the vertical, central channel is substantially perpendicular to the flux direction so that when current is flowing and there is a magnetic field in the flow of melt, a force (F) is produced on the melt either in the direction of the bottom channel or in the side or the vertical, central channel, directed upwardly or downwardly along this channel.

Claim 5

In a furnace as claimed in claim 1, where the channel or channels have a circulation portion and a teeming tap hole and a portion of the channel or channels directed from and towards and the tap hole, said magnetic flux being arranged at the last-mentioned portions of the channel near the circulation portion, thus together with the current in said portion producing a force from or towards said tap hole.

Claim 6

A furnace according to claim 4 in which the channel with molten metal comprises the secondary circuit of a transformer, the lowest part containing the tap hole with the magnetic flux perpendicular to the current near the tap hole.

Claim 7

An electro-magnetic valve for tapping off molten metal or alloy from the bottom of a furnace of the submerged resistor type according to claim 4, comprising at least one bottom channel and at least two side channels and a central channel leading from the bottom channel to the hearth, characterized in that close to the bottom channel near the central channel, near one or more tapping holes for the melt, one or more magnetic circuits are arranged with a flux direction straight across the tapping holes and having an ''''air gap'''' in the melt, and that when a current is flowing in the melt across the flux direction, a force is produced close to the tapping hole on the melt in the central channel and metal flow, directed upwardly or downwardly.