GB2058528A - Electroslag remelting apparatus - Google Patents

Abstract

An electrode feeding device 5 includes a lower holder 6 with a roller feed 12, and an upper holder in the form of a magazine 8 with a vertical shaft 16 and with axial sockets 21 accommodating vertical electrode blanks 9, each supported by a gate 22. A welding head 10 connects a consumable electrode 7 to a blank 9 brought into abutting contact by means of the holders, whereby a continually extended electrode 7 is continuously fed into the cavity of a mould 1, e.g. in the production of large ingots. <IMAGE>

Description

SPECIFICATION Electroslag remelting apparatus The invention provides electroslag remelting apparatus including an electrode feeding device mounted on a supporting stand and comprising a lower holder with a roller feeding means having at least two pairs of drive rollers intended for friction contact with the surface of the consumable electrode fed by the rollers into a mould cavity, an upper holder disposed above the lower holder and being in the form of a rotatable drum with a vertical shaft mounted on the supporting stand, with through sockets to accommodate vertically oriented electrode blanks, the sockets being arranged in a circle passing through the vertical axis of symmetry of the rollerfeeding means of the lower holder, and with gates arranged on the bottom end face of the rotatable drum and intended to support the electrode blanks in the sockets, and also comprising a means for joining together the consumable electrode and an electrode blank which are brought into abutting contact with the aid of the lower holder and the upper holder, said means being arranged between the holders.

Such a construction of the electroslag remelting apparatus enables the electroslag process to be conducted uninterruptedly, building up the consumable electrode, as it is remelted, by measured-length blanks whose number in the rotatable magazine of the elctrode feeding device may be a multiple of the number of such blanks required to produce an ingot.

The provision of the roller feeding means in the lower holder in conjunction with the receivers and gates in the rotatable magazine of the upper holder makes it possible to do without clamps for the consumable electrode and electrode blank, to dispense with vertical movements of the holders, to reduce accordingly current leads and, as a result, to simplify the procedure of building up the consumable electrode, and to ensure safety for operators.

In addition, the above-described construction of the electrode feeding device of the apparatus makes possible a complete automation of the auxiliary operation.

It is advantageous for the rotatable magazine to be an exchangeable one, as this permits its loading outside the apparatus and thus shortens the intervals between remeltings.

The rotatable magazine may be made in the form of a pair of horizontal disks mounted one above the other on a hub put on a vertical shaft, each of the electrode-blank receivers being a pair of aligned apertures provided in the disks.

To effect an automatic feed of electrode blanks to the point of the abutting contact of each next blank with the consumable electrode, it is preferable for the electrode feeding device to be provided with a detector to detect the moment of emergence of a blank from the rotatable drum, the detector being coupled to the drum rotation drive and installed approximately at the level of the gates. In addition, the electrode feeding device may incorporate a positive stop, installed on the lower holder and adapted to open one of the gates when it has been carried by the rotatable drum to the position over the consumable electrode, and a detector indicating when the electrode blank comes in contact with the consumable electrode, this detector being coupled to the means for joining these latter and being mounted on the lower holder near the point of the abutting contact.

The invention will now be described by way of exampie with reference to the accompanying drawings, in which: Figure 1 shows a general view of an electroslag remelting apparatus, partly in vertical section; and Figure 2 is a section taken along the line Il-Il in Figure 1, on an enlarged scale.

The electroslag remelting apparatus illustrated comprises a mould 1 whose cavity (confined by walls 2 and a bottom plate 3) forms a melting space for a slag bath and a metal bath for forming a solidifying ingot, a supporting stand 4 installed close to the mould 1 and being a casting or a welded structure whose height exceeds that of the mould 1, and an electrode feeding device 5 mounted on the supporting stand 4.

The electrode feeding device 5 includes: a lower holder 6 intended for holding and guiding a consumable electrode 7 and for feeding it into the cavity of the mould 1; an upper holder made in the form of a rotatable drum 8 which serves as a magazine for electrode blanks 9 and is also intended for bringing one of these blanks into abutting contact with the consumable electrode 7 and holding this blank while it is being joined to the electrode; and welding head 10 for joining the electrode blank 9 to the consumable electrode 7, the welding head 10 being arranged between the upper and the lower holder.

The lower holder 6 comprises a horizontal bracket 11 fixedly attached to the stand 4 and a roller feeding means 1 2 incorporating at least two pairs of drive rollers 13 carried by fixed axles 14 mounted on the horizontal bracket 11 (the roller drive is not shown). The horizontal spacing of the drive rollers 1 3 is selected so that they come in frictional contact with the consumable electrode 7, interposed between them, to effect vertical movement of the electrode 7 by rotation of the rollers.

The drum 8 comprises a hub 1 5 fixed on a vertical shaft 1 6 mounted in rolling-contact bearings 1 7 fitted in the top portion of the stand 4.

The hub 1 5 carries upper and lower horizontal disks 18 and 19, fixedly attached and each having apertures 20 aligned in pairs to define axial sockets 21 for accommodating the vertically orientated blanks 9.

The diameter of the apertures 20 in the lower disk 1 9 is somewhat larger than that of respective aligned apertures in the upper disk 1 8 and exceeds the diameter of the electrode blank 9 by approximately 10% of the latter diameter; the height of each aperture in the upper disk 1 8 is less than the electrode blank diameter.

One end of the electrode blank 9 is shaped as a protruding cone while the other end is formed with a conical recess, the vertex angle of the protruding cone being less than that of the conical recess. With such a configuration of the blank, the above-specified relation between the dimensions of the apertures 20 of the socket 21 provides for self-centering of the electrode blank 9 on the end face of the consumable electrode 7 installed in the lower holder 6, when the blank 9 and the electrode 7 are aligned. The sockets 21 are arranged in a circle with respect to the axis of the vertical shaft 16, the circle passing thro'ugh the vertical median axis of the roller feeding means 12, which in this particular case coincides with the axis of symmetry of the mould 1.

The number of the sockets 21 in the drum 8 is selected to be equal to, or a multiple of, the number of the electrode blanks 9 required to produce an ingot. The lower disk 19 carries, on its bottom end face, gates 22 which close the sockets 21 from below and serve to support the electrode blanks 9 accommodated in the sockets.

The vertical shaft 1 6 is operatively connected with a drum rotation drive 23 mounted on the stand 4 and comprising an electric motor, a speed reducer, and a gear pair, or being of some other conventional construction.

In the preferred embodiment the drum 8 is removable from the vertical shaft 16. To enable the transmission of torque from the shaft 16 to the drum 8, the shaft is fitted with a key 24. The hub 1 5 of the drum 8 is provided with a retainer 25 which ensures a positive connection of the drum to the shaft 1 6 and prevents the drum from vibrating during its rotation.

The welding head 10 serving to join the electrode blank 9 to the consumable electrode 7 has a base 26 pivotally mounted on the horizontal bracket 11 of the lower holder 6 and made in the form of a segment gear operatively connected with a rotation drive (not shown). The pivoted base 26 carries a housing 27 comprising a post 28 supporting a guiding nozzle 29 through which passes a welding wire 30 unwound from a reel 31 by a wire feeding device 32. The inner space of the nozzle 29 communicates with a carbon dioxide feed system (not shown).

Any conventional welding head or any conventional welding method, for producing a permanent joint (e.g. electroslag welding), may be used for joining an electrode blank 9 to the consumable electrode 7.

The apparatus has a power source 33 connected to the bottom plate 3 of the mould 1 and to one of the fixed axles 14 of the roller feeding means 12 of the lower holder 6.

In the preferred embodiment the electrode feeding device 5 includes a detector 34 for detecting the moment of emergence of the electrode blank 9 from the lower disk 1 9 of the drum 8, the detector being a photo-switch or any other suitable device electrically coupled to the drum rotation drive 23. The detector 34 is disposed approximately at the level of the gate 22 and is mounted on a support 35 fixedly attached to the stand 4. The detector 34 is intended to control the rotation of the drum 8.

The bracket 11 of the lower holder 6 carries a fixed stop 36 formed as a vertical rod and intended to open one of the gates 22 (Figure 2).

The spacing of the stop 36 from the axis of the vertical shaft 1 6 and from the axis of rotation of the gate 22 is selected such that the gate 22 fully opens the respective socket 21 at the moment when the drum 8 occupies the position in which the next blank 9 becomes aligned with the electrode 7 to be built up.

Operation of the welding head 10 is controlled by a detector 37 which detects abutting of the electrode blank 9 against the consumable electrode 7 (Figure 1) and comprises a limit switch 38 mounted on a support 39 fixedly attached to the bracket 11. The height of the support 39 is selected such that the limit switch drive is slightly above the pointed portion of the blank 9 when the blank bears against the end face of the consumable electrode 7 being melted down. The limit swtich 38 is electricaily coupled with the drive of pivoting motion of the welding head 10 and with the power source (not shown) of the welding head.

Before starting the remelting process or, when the drum 8 is exchangeable, while the preceding ingot is being produced, the electrode blanks 9 are placed into the sockets 21 of the drum 8 so that their pointed ends rest on the gates 22. Then the drum 8 is put onto the vertical shaft 1 6 and locked in position by the retainer 25.

On aligning one of the blanks with the mould axis, this blank is introduced into the cavity of the mould 1, where a slag bath 40 has been established beforehand. Next, the voltage is applied from the power source 33 to the fixed axle 14 of one of the rollers 13 of the feeding means 12 and to the bottom plate 3 of the mould 1. The heat generated in the slag by the electric current passing through it fuses the blank 9 introduced into the mould 1 and acting thus as the consumable electrode 7, and the molten metal flows down onto the bottom plate 3 of the mould 1 to solidify into an ingot 41.

At the moment when the roller feeding means 12, moving the consumable electrode 7 downwardly as it is fused down, withdraws its top end out of the socket 21 of the drum 8, the detector 34 switches on the drum rotation drive 23.

As the drum 8 is rotated, the gate 22 which closes the socket 21 accommodating the next blank 9 runs onto the fixed stop 36 and turns to fully open the socket 21 by the moment of aligning the blank 9 with the mould axis (Figure 2).

Descending under gravity into abutting contact with the top end of the consumable electrode 7 (Figure 1), the electrode blank 9 moves past the detector 34, which delivers a signal to switch off the electric motor of the drive 23 and thus to stop rotating the drum 8.

The blank 9 centers itself with its pointed end in the conical recess in the end face of the consumable electrode 7, the self-centering being faciliated by the above-specified relation between the dimensions of the apertures 20 of the socket 21. As it moves towards the end face of the consumable electrode 7, the blank 9 depresses the drive element of the limit switch 38 which switches on the power source (not shown), the drive of pivoting motion on the base 26, and the wire feeding device 32 of the welding head 10.

The welding head 10, rotating about the mould axis on the pivoted based 26, welds the consumable electrode 7 and the electrode blank 9 together so that the weld seam fills the gap between the surfaces of the concial point of the blank 9 and of the conical recess of the consumable electrode 7 over the greater part of the circle. Then the above devices of the welding head 10 are switched off, and the now-extended consumable electrode advances into the cavity of the mould 1 as one integral piece, and comes out of the socket 21 in the drum 8, whereupon the drum rotation drive 23 is switched on, on command from the detector 34, and the drum 8 is rotated until the axis of the next electrode blank 9 is aligned with the mould axis; then this blank 9 is brought into contact with the electrode 7 and welded thereto in the manner described above.

The above-described apparatus is more efficient for producing large ingots requiring the remelting of a great number of electrodes.

Claims (9)

1. Electroslag remelting apparatus including an electrode feeding device which comprises a lower holder provided with feeding means having at least two pairs of drive rollers intended for frictional contact with the surface of a consumable electrode to be fed downwards by the rollers, an upper holder in the form of a magazine which is rotatable about a vertical axis and which has receivers for accommodating vertically orientated electrode blanks arranged on a circle passing through the vertical median axis of the feeding means of the lower holder, gates arranged at the bottom end of the magazine to support the respective electrode blanks in the sockets, and means for joining together the upper end of a consumable electrode to the lower end of a selected electrode blank brought into abutting contact with the consumable electrode with the aid of the lower holder, the upper holder, and the associated gate, which means is arranged between the holders.

2. Apparatus as claimed in claim 1, wherein the magazine is exchangeable.

3. Apparatus as claimed in claim 1 or 2, wherein the magazine comprises two horizontal disks mounted one above another on a hub, each of the receivers being constituted by aligned holes provided in the respective disks.

4. Apparatus as claimed in any of claims 1 to 3, wherein the electrode feeding device includes a rotation drive operatively connected with the magazine and a detector adapted to detect the emergence of the selected electrode blank from the magazine drum, the detector being coupled with the said drive and installed substantially at the level of the associated gate.

5. Apparatus as claimed in any of claims 1 to 4, wherein the electrode feeding device includes a fixed stop adapted to open one of the gates when it is brought by the rotatable drum to the position of location of the consumable electrode, the stop being installed on the lower holder.

6. Apparatus as claimed in any of claims 1 to 5, wherein the electrode feeding device includes a detector adapted to detect abutting of the selected electrode blank against the consumable electrode, coupled with the means for joining these latter together.

7. Electroslag remelting apparatus substantially as described with reference to, and as illustrated in, the accompanying drawings.

8. Apparatus as claimed in any of claims 1 to 7, including electrode blanks accommodated in the receivers, each blank having a conical recess at one end and a conical point with a smaller vertex angle at the other end.

8. An electrode used in the apparatus according to any of the preceding claims substantially as described with reference to, and as illustrated in, the accompanying drawings.

9. An electrode blank for use in the apparatus according to claim 1, having a conical recess at one end and a conical point with a smaller vertex angle at the other end.

New claims or amendments to claims filed on 13/8/80 Superseded claims 8 and

9. New or amended claims: