Patent ID: 12256476

DESCRIPTION OF EMBODIMENTS

FIG.1shows a schematic view of a device1for the inductive heating of a metallic workpiece2, in particular a flat material, in a rolling mill. The device1has a converter3for producing an alternating voltage, in particular a two-phase alternating voltage, with a specific frequency and a specific amplitude. The converter3is accommodated in a fixedly arranged housing4next to the rolling mill. The alternating voltage is fed by way of two conductor rails5from the converter3to a capacitor bank6comprising a plurality of capacitors7connected in parallel. The capacitor bank6is likewise arranged within the housing4. The interior of the housing4may be air-conditioned, in particular cooled. Furthermore, the housing is for example secured by a door or some other access system, so that unauthorized persons do not gain access to the electrical devices in the interior of the housing4.

In this way, the converter3and the capacitor bank6are accommodated in a clean, dry and air-conditioned environment and are actively protected from heat from the rolling mill.

Use of the conductor rails5for connecting the capacitor bank6to the converter3is possible since no relative movement between the capacitor bank6and the converter3is required. In this way it is possible to dispense with long cable connections at this point, whereby electrical losses are reduced.

The housing4, as it is shown, is arranged next to a working zone8or a coil car9of the rolling mill for rolling flat material. It is possible for the housing4to be located below (seeFIG.2) or above (seeFIG.3) the working zone8or the coil car9. In addition to a horizontal offset, the housing may also have a vertical offset in relation to the working zone8or the coil car9. Arranged in the working zone8is a coil car9. Arranged in the coil car9are an upper coil10and a lower coil11, between which the workpiece2can be moved through. The direction of movement of the workpiece2inFIG.1is perpendicular to the plane of the image that is toward the viewer or away from the viewer. The coils10,11are electrically connected to the capacitor bank6by a respective flexible cable12,13. In the embodiment shown, the conductor rails5are led out of the housing4beyond the capacitor bank6and the cables12,13are connected to the conductor rails5outside the housing4.

The flexible cables12,13allow relative movement of the connected coils10,11with respect to the housing4.

In an alternative embodiment that is not shown, the cables12,13may be led into the housing4and connected there to the capacitor bank6.

In an alternative embodiment that is not shown, a common cable is provided for connecting the two coils10,11to the capacitor bank.

The cables12,13may be formed as coaxial cables (seeFIG.4), wherein one phase of the alternating voltage is on an inner conductor and the other phase of the alternating voltage is on an outer conductor. Furthermore, the cables12,13may be water-cooled. In this way, the electrical resistance of the cable12,13and the development of heat can be reduced and the current flow can be increased. The coaxial cable reduces a magnetic stray field, so that the electromagnetic compatibility with nearby devices is improved.

The coils10,11are adjustable in height within the coil car9, for example by hydraulic, pneumatic or electromechanical height-adjusting elements14. In this way, a distance between the coils10,11and the workpiece2can be set. The coil car9can be moved as a whole in a transverse direction, transversely to the direction of movement of the workpiece2, that is away from the housing4or toward it, for example by at least one hydraulic, pneumatic or electromechanical transverse-adjusting element15. This is arranged for example on the side of the coil car9that is facing away from the housing4. The coil car9is moved by its wheels. In this way, the available space, accessibility and ease of maintenance can be improved.

In one embodiment, the cables12,13are connected to the coils10,11on the side of the coil car9that is facing the housing4. In this way, the length of the cables12,13can be minimized and electrical losses correspondingly reduced.

Similarly, further media connections, for example for compressed air, water and/or hydraulics, can be provided on the side of the coil car9.

In an embodiment shown inFIGS.2and3, the coil car9is designed as open on one side, so that it can be moved out completely from the mill, even while the strip is running through. Similarly, the coil car9can be moved out of the mill during breaks in production, in order to easily exchange the coils10,11there. Quick-action couplings may be provided for the cables12,13, in order to disconnect them from the coils10,11in an easy way.

The device1may be arranged in the rolling mill, for example a combined casting and rolling mill of the Arvedi ESP type, for example between two rolling stages, i.e. between the roughing rolling train and the finishing rolling train.

If an accidental arc occurs in the converter3or in the capacitor bank6, the excess pressure in the interior of the housing4is discharged to the outside through a shaft17. As a result, vapors, which are sometimes toxic, are kept away from the rolling mill and the operating crew. The shaft17is closed by an explosion flap18, so that the housing4can be air-conditioned without any problem.

FIGS.2and3respectively show a schematic view of a second and third device1for the inductive heating of a metallic workpiece2, wherein the housings4are arranged inFIG.2below and inFIG.3above the working zone8. The coil cars9inFIGS.2and3are open on one side, so that the coil car9can be moved out to the side, in order, for example, to rectify a fault in the rolling mill.

FIG.4schematically shows a cross section through a cable12,13, specifically a water-cooled coaxial cable27. The inner and the outer conductor28,29of the cable comprises inner and outer wires23,20, typically of copper or a copper alloy. The cable12,13is insulated with respect to the surroundings by an outer cable sheath19. In order to be able to remove heat from the inner and outer conductors28,29, the spaces between the outer cable sheath19and the intermediate sheath22and between the intermediate sheath22and the inner conductor28are flowed through by a cooling fluid, here cooling water21.

FIG.5shows a diagram of a cooling circuit for the active water cooling of a flexible coaxial cable27,12,13fromFIG.4. The cooling water is fed to the coaxial cable27,12,13from a water tank24by a water pump25and cools the cable. After flowing through the cable, the cooling water is cooled by a heat exchanger, for example a water-air heat exchanger, or a water-water heat exchanger, and fed back to the water tank.

The cooling water is typically a liquid, water-based coolant with additives, in order to improve the electrical insulating effect and the aging resistance of the cooling water.

Although the invention has been illustrated more specifically and described in detail by the preferred exemplary embodiment, the invention is not restricted by the examples disclosed and other variations may be derived therefrom by a person skilled in the art without departing from the scope of protection of the invention.

LIST OF DESIGNATIONS

1Device2Workpiece3Converter4Housing5Conductor rail6Capacitor bank7Capacitor8Working zone9Coil car10Upper coil11Lower coil12Cable13Cable14Height-adjusting element15Transverse-adjusting element16Converter cabinet17Shaft18Explosion flap19Outer cable sheath20Outer wires21Cooling water22Intermediate sheath23Inner wires24Water tank25Water pump26Heat exchanger27Coaxial cable28Inner conductor29Outer conductor