Patent GB-1513342-A (GB)
Title: Electroslag remelting plant and method
IPC: B22D23/10
Filed: 1976-05-04
Abstract: 1513342 Electroslag heating VENJUKOV ARMATURNY ZAVOD 4 May 1976 18131/76 Heading H5H [Also in Division B3] In an electroslag melting process in which a consumable electrode 4 and a non-consumable (graphite) hollow electrode 8, mounted on and electrically insulated from moulding means comprising a mould 16 and an optional mandrel 24, depend into a slag bath 7 contained in the cooled mould 16, remelting of the electrode 4 is achieved by passing current from source 11 to the slag bath 7 via the series connected electrodes 4 and 8 whilst the base plate 6 and non-consumable electrode 8 undergo relative vertical displacement. Either electrode 8 may be movable on carriage 10 as shown, or baseplate 6 may be movable by transfer gear. The non-consumable electrode 8 carried by the mould thermally insulates the inside wall of the mould from the slag. The non-consumable electrode is electrically insulated from the mould by an insulating layer 17. Mould and non-consumable electrode are vertically movable together and the base plate may be movable. The non-consumable electrode may be a hollow rod or may be formed as arcuate plates arranged in electrical insulation to form a cylindrical array (Fig. 3, not shown). For forming a small cross-sectional area ingot (e.g. slab or metal strip) from a larger cross-sectional area consumable electrode (Fig. 4, not shown) the consumable electrode depends into a slag bath contained in a flared mould on which is seated a non-consumable hollow electrode. Both the consumable electrode and the non-consumable electrode mould travel upwardly at rates which can be readily calculated to maintain the tips of the non- consumable and consumable electrodes constantly immersed in the slag bath. If the non-consumable electrode and mould are maintained stationary, the bottom plate moves downwardly and the non- consumable electrode moves downwardly at rates to maintain the electrode tips immersed in the slag bath. For the production of tubes 33 (Fig. 17) a ring of consumable electrode rods or a cylindrical electrode 26 depends into an annular space defined between the non-consumable electrode 23 and the mould 13. A mandrel 24, electrically insulated from the hollow non-consumable electrode 23 is supported with electrode 23 on the mould 13. The electrode 23 thermally insulates the mandrel 24. The base plate 6 as shown, or the mould 13, mandrel 24 and non-consumable electrode 23 are vertically movable during the process to maintain the electrodes 23, 26 immersed constantly in the slag bath 7. In a further arrangement, in addition to the hollow electrode 23 about mandrel 24, a further non-consumable hollow electrode connected in parallel with electrode 23, is electrically insulated from mould 13 on which it is carried. In some embodiments, to produce longer ingots, once the bottom plate has been lowered to its maximum extent whilst the mould, non-consumable electrode, and mandrel are held stationary, the mould, non-consumable electrode and mandrel are moved upwardly so that the ingot is produced in two steps. To produce a hollow casting with a closed bottom, a switch is provided to connect the consumable electrode and base plate in series at the commencement of the process to provide a bottom of a required thickness. Once the bottom is formed, the switch is actuated to connect the non-consumable electrode and consumable electrode in series so that with the aid of a mandrel the remainder of the casting may be formed. Complex hollow castings with projecting portions may be produced in a plant with a stationary mould. A switch initially connects the consumable electrode and base plate in series to form a closed bottom for the casting whereupon the switch is actuated to connect the non-consumable and consumable electrodes in series. The non-consumable electrode and mandrel secured therein are carried upwardly so that they remain constantly in the slag bath. For forming a large ingot from a succession of consumable electrodes, a changeover switch connects the base plate and non-consumable electrode in series during electrode replacement. An ingot may be united to a preformed metal member to form a complex casting by passing the preformed metal member through an aperture in the base plate, passing current through the non-consumable electrode and the preformed metal member via the slag to melt the surface of the preformed member and then melting the consumable electrode by connecting it in series with the non-consumable electrode to form the ingot.