DEVICE FOR THE INDUCTIVE HEATING OF A WORKPIECE IN A ROLLING MILL

Abstract

A device (1) for inductive heating of a workpiece (2) in a rolling mill, the device (1) including: a converter (3) for creating an alternating voltage, a capacitor bank (6) electrically connected to the converter (3), and having a plurality of capacitors (7) connected in parallel, a working field (8), in which an upper coil (10) and a lower coil (11) are arranged. The workpiece (2) is able to be passed between the coils (10, 11) and is thereby inductively heated by cross-field heating. A housing (4) arranged next to, below or above the working field (8). The converter (3) and capacitor bank (6) are arranged in the housing (4). The coils (10, 11) are each electrically connected to the capacitor bank (6) by a flexible cable (12, 13). The cable (12, 13) is a coaxial cable (27), with one phase of the alternating voltage applied to an inner conductor (28) and the other phase of the alternating voltage applied to an outer conductor (29) of the coaxial cable (27). The cables (12, 13) are cooled by a fluid, such as air or water (21).

Claims

1. A device for inductive heating of a workpiece in a rolling mill, wherein the device comprises: a converter for producing an alternating voltage, a capacitor bank electrically connected to the converter and the capacitor bank comprising a plurality of capacitors connected in parallel, a working zone, in which an upper coil and a lower coil are arranged, wherein the workpiece can be moved through between the coils such that the workpiece is thereby inductively heated by transverse-field heating, a housing arranged next to, below or above the working zone, wherein the converter and the capacitor bank are arranged in the housing, the coils are electrically connected to the capacitor bank by a respective flexible cable, the cables are configured as coaxial cables, wherein one phase of the alternating voltage is on an inner conductor and another phase of the alternating voltage is on an outer conductor of each of the coaxial cables, and the cables are configured to be cooled by a fluid.

2. The device as claimed in claim 1, further comprising at least two conductor rails; the converter and the capacitor bank are electrically connected to one another by the conductor rails.

3. The device as claimed in claim 1, further comprising a coil car in which the coils are arranged together.

4. The device as claimed in claim 1, further comprising an air-conditioning unit operable to control air conditions in an interior of the housing.

5. The device as claimed in claim 3, wherein the coil car comprises at least one height-adjusting element configured for the height adjusting the coils with respect to the workpiece.

6. The device as claimed in claim 3, wherein the coil car comprises at least one transverse-adjusting element configured for moving the coil car in a transverse direction of the workpiece.

7. The device as claimed in claim 6, wherein the transverse-adjusting element is arranged on a side of the coil car that is facing away from the cables.

8. The device as claimed in claim 3, wherein the cables are connected to the coils on a side of the coil car that is facing the housing.

9. The device as claimed in claim 1, further comprising a converter cabinet in which the converter is arranged, and the converter cabinet is located within the housing.

10. The device as claimed in claim 1, further comprising a shaft to which the housing is connected, so that in the event of an accidental arc, an excess pressure in the interior of the housing can be discharged to the outside by way of the shaft.

11. The device as claimed in claim 10, further comprising an explosion flap, the shaft is operable to be closed during normal operation.

12. The device of claim 1, wherein the fluid for cooling the cables comprises air or water.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 shows a schematic view of a first device for the inductive heating of a workpiece,

[0037] FIG. 2 shows a schematic view of a second device for the inductive heating of a workpiece,

[0038] FIG. 3 shows a schematic view of a third device for the inductive heating of a workpiece,

[0039] FIG. 4 shows a schematic view of a cross section through a water-cooled coaxial cable, and

[0040] FIG. 5 shows a diagram of the active water cooling of a coaxial cable.

DESCRIPTION OF EMBODIMENTS

[0041] FIG. 1 shows a schematic view of a device 1 for the inductive heating of a metallic workpiece 2, in particular a flat material, in a rolling mill. The device 1 has a converter 3 for producing an alternating voltage, in particular a two-phase alternating voltage, with a specific frequency and a specific amplitude. The converter 3 is accommodated in a fixedly arranged housing 4 next to the rolling mill. The alternating voltage is fed by way of two conductor rails 5 from the converter 3 to a capacitor bank 6 comprising a plurality of capacitors 7 connected in parallel. The capacitor bank 6 is likewise arranged within the housing 4. The interior of the housing 4 may 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 housing 4.

[0042] In this way, the converter 3 and the capacitor bank 6 are accommodated in a clean, dry and air-conditioned environment and are actively protected from heat from the rolling mill.

[0043] Use of the conductor rails 5 for connecting the capacitor bank 6 to the converter 3 is possible since no relative movement between the capacitor bank 6 and the converter 3 is required. In this way it is possible to dispense with long cable connections at this point, whereby electrical losses are reduced.

[0044] The housing 4, as it is shown, is arranged next to a working zone 8 or a coil car 9 of the rolling mill for rolling flat material. It is possible for the housing 4 to be located below (see FIG. 2) or above (see FIG. 3) the working zone 8 or the coil car 9. In addition to a horizontal offset, the housing may also have a vertical offset in relation to the working zone 8 or the coil car 9. Arranged in the working zone 8 is a coil car 9. Arranged in the coil car 9 are an upper coil 10 and a lower coil 11, between which the workpiece 2 can be moved through. The direction of movement of the workpiece 2 in FIG. 1 is perpendicular to the plane of the image that is toward the viewer or away from the viewer. The coils 10, 11 are electrically connected to the capacitor bank 6 by a respective flexible cable 12, 13. In the embodiment shown, the conductor rails 5 are led out of the housing 4 beyond the capacitor bank 6 and the cables 12, 13 are connected to the conductor rails 5 outside the housing 4.

[0045] The flexible cables 12, 13 allow relative movement of the connected coils 10, 11 with respect to the housing 4.

[0046] In an alternative embodiment that is not shown, the cables 12, 13 may be led into the housing 4 and connected there to the capacitor bank 6.

[0047] In an alternative embodiment that is not shown, a common cable is provided for connecting the two coils 10, 11 to the capacitor bank.

[0048] The cables 12, 13 may be formed as coaxial cables (see FIG. 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 cables 12, 13 may be water-cooled. In this way, the electrical resistance of the cable 12, 13 and 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.

[0049] The coils 10, 11 are adjustable in height within the coil car 9, for example by hydraulic, pneumatic or electromechanical height-adjusting elements 14. In this way, a distance between the coils 10, 11 and the workpiece 2 can be set. The coil car 9 can be moved as a whole in a transverse direction, transversely to the direction of movement of the workpiece 2, that is away from the housing 4 or toward it, for example by at least one hydraulic, pneumatic or electromechanical transverse-adjusting element 15. This is arranged for example on the side of the coil car 9 that is facing away from the housing 4. The coil car 9 is moved by its wheels. In this way, the available space, accessibility and ease of maintenance can be improved.

[0050] In one embodiment, the cables 12, 13 are connected to the coils 10, 11 on the side of the coil car 9 that is facing the housing 4. In this way, the length of the cables 12, 13 can be minimized and electrical losses correspondingly reduced.

[0051] Similarly, further media connections, for example for compressed air, water and/or hydraulics, can be provided on the side of the coil car 9.

[0052] In an embodiment shown in FIGS. 2 and 3, the coil car 9 is 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 car 9 can be moved out of the mill during breaks in production, in order to easily exchange the coils 10, 11 there. Quick-action couplings may be provided for the cables 12, 13, in order to disconnect them from the coils 10, 11 in an easy way.

[0053] The device 1 may 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.

[0054] If an accidental arc occurs in the converter 3 or in the capacitor bank 6, the excess pressure in the interior of the housing 4 is discharged to the outside through a shaft 17. As a result, vapors, which are sometimes toxic, are kept away from the rolling mill and the operating crew. The shaft 17 is closed by an explosion flap 18, so that the housing 4 can be air-conditioned without any problem.

[0055] FIGS. 2 and 3 respectively show a schematic view of a second and third device 1 for the inductive heating of a metallic workpiece 2, wherein the housings 4 are arranged in FIG. 2 below and in FIG. 3 above the working zone 8. The coil cars 9 in FIGS. 2 and 3 are open on one side, so that the coil car 9 can be moved out to the side, in order, for example, to rectify a fault in the rolling mill.

[0056] FIG. 4 schematically shows a cross section through a cable 12, 13, specifically a water-cooled coaxial cable 27. The inner and the outer conductor 28, 29 of the cable comprises inner and outer wires 23, 20, typically of copper or a copper alloy. The cable 12, 13 is insulated with respect to the surroundings by an outer cable sheath 19. In order to be able to remove heat from the inner and outer conductors 28, 29, the spaces between the outer cable sheath 19 and the intermediate sheath 22 and between the intermediate sheath 22 and the inner conductor 28 are flowed through by a cooling fluid, here cooling water 21.

[0057] FIG. 5 shows a diagram of a cooling circuit for the active water cooling of a flexible coaxial cable 27, 12, 13 from FIG. 4. The cooling water is fed to the coaxial cable 27, 12, 13 from a water tank 24 by a water pump 25 and 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.

[0058] 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.

[0059] 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

[0060] 1 Device

[0061] 2 Workpiece

[0062] 3 Converter

[0063] 4 Housing

[0064] 5 Conductor rail

[0065] 6 Capacitor bank

[0066] 7 Capacitor

[0067] 8 Working zone

[0068] 9 Coil car

[0069] 10 Upper coil

[0070] 11 Lower coil

[0071] 12 Cable

[0072] 13 Cable

[0073] 14 Height-adjusting element

[0074] 15 Transverse-adjusting element

[0075] 16 Converter cabinet

[0076] 17 Shaft

[0077] 18 Explosion flap

[0078] 19 Outer cable sheath

[0079] 20 Outer wires

[0080] 21 Cooling water

[0081] 22 Intermediate sheath

[0082] 23 Inner wires

[0083] 24 Water tank

[0084] 25 Water pump

[0085] 26 Heat exchanger

[0086] 27 Coaxial cable

[0087] 28 Inner conductor

[0088] 29 Outer conductor