WO2023194520A1

WO2023194520A1 - Scrap charging device for charging scrap in a crucible of a vacuum melting apparatus

Info

Publication number: WO2023194520A1
Application number: PCT/EP2023/059107
Authority: WO
Inventors: Matthias KNABL; Angelico Della Negra
Original assignee: Danieli and C Officine Meccaniche SpA
Current assignee: Danieli and C Officine Meccaniche SpA
Priority date: 2022-04-07
Filing date: 2023-04-06
Publication date: 2023-10-12
Anticipated expiration: 2024-10-07
Also published as: IT202200006914A1

Abstract

Scrap charging device (80) to charge scrap (90) in a crucible (81) of a vacuum-melting apparatus (8), said scrap (90) being bound with a wire (9); the device (80) comprising - a first tubular body (1) defining a vertical axis (Y); - a second tubular body (2) arranged coaxially inside or outside said first tubular body (1); - first actuating means (41) adapted to translate the first tubular body (1) and the second tubular body (2) along said vertical axis (Y); - second actuating means (42) adapted to rotate the second tubular body (2) with respect to the first tubular body (1) or vice versa, about said vertical axis (Y); wherein the lower end (19) of the wall (10) of the first tubular body (1) has at least one opening (11a, 11b) shaped so that said lower end (19) has at least one protrusion (12a, 12b) along said at least one opening (11a, 11b), so that the wire (9) which bounds the scrap (90) can pass through said at least one opening (11a, 11b) and be suspended on said at least one protrusion (12a, 12b); wherein the lower end (29) of the wall (20) of the second tubular body (2) has at least one opening (21a, 21b); wherein the device (80), according to the angular position of the second tubular body (2) with respect the first tubular body (1), can take a loading position which allows to pass the wire (9) through said at least one opening (11a, 11b) of the first tubular body (1) and through said at least one opening (21a, 21b) of the second tubular body (2), and which allows to suspend the wire (9) on said at least one protrusion (12a, 12b); and wherein said second tubular body (2) is adapted to be rotated, in a first direction of rotation, from said loading position to a locking position, wherein the wall (20) of the second tubular body (2) at least partially obstructs the opening (11a, 11b) of the first tubular body (1) so as to prevent the wire (9) suspended on the protrusion (12a, 12b) from leaving said at least one protrusion (12a, 12b); and is adapted to be rotated in a second direction of rotation, opposite to the first direction of rotation, from said locking position to a release position allowing the release of the wire (9) from said at least one protrusion (12a, 12b).

Description

SCRAP CHARGING DEVICE FOR CHARGING SCRAP IN A CRUCIBLE OF A VACUUM MELTING APPARATUS

Field of the invention

The present invention relates to the field of vacuum melting, in particular vacuum induction melting (VIM).

In particular, the invention relates to a device for charging scrap in a crucible of a vacuum melting apparatus. The invention also relates to an apparatus comprising such device and to a method of charging scrap by means of such device.

Background of the invention

Vacuum induction melting (VIM) is a known process which involves melting of metal under vacuum in an induction-heated crucible.

VIM is typically employed to produce high quality alloys and articles, such as blades for gas turbine engines or precision casting parts, by casting molten material under vacuum.

The charging material in a VIM furnace often comprises high value scrap and leftovers from casting processes.

To-date, charging of scrap is typically done with a charging winch, i.e. a steel rope with a hook on a driven drum.

The scrap is bound with a self-burning rope or aluminum/tin wire which burns or melts at a certain point above the crucible due to heat radiation. Alternatively, the scrap can be placed in a bucket having a bottom, e.g. having an orange peel design, closed by a self-burning cotton rope or aluminum/tin wire. The bottom of the bucket can alternatively comprise a mesh made of aluminum, which melts due to heat radiation above the liquid melt.

The wire, or rope, which binds the scrap or the bucket is then hung on the hook. The hook with the hanging rope or bucket is lowered towards the crucible and the scrap falls down in the crucible when the wire burns or melt.

Disadvantageously, there is no controlled release of the scrap into the crucible.

Disadvantageously, the scrap always falls down in the crucible causing splashes and damages to the crucible wall or bottom. This leads to a loss of particles of refractory material which are detrimental for the melt quality and cause wear of the refractory. Even breaking of the refractory crucible can occur.

Furthermore, the use of the winch does not allow a controlled release from a defined height and at defined speed. The operator lowers the winch with visual control. A precise position of the scrap within the crucible cannot be defined - the rope on the drum does not allow that.

Also, disadvantageously, with the known charging system, automation of the charging process is hardly possible.

The need is therefore felt to improve the system to charge the scrap, or more generally to charge the charging material, in the crucible of a vacuum melting apparatus.

Summary of the invention

It is an object of the present invention to provide a device which allows to improve the way the scrap, or more generally the charging material, is charged in the crucible of a vacuum melting apparatus.

In particular, it is an object of the invention to provide a device which allows a controlled release of the scrap into the crucible, in particular avoiding splashes and damages to the crucible.

The present invention achieves at least one of such objects, and others which will become apparent from the present description, by providing a scrap charging device, or device for charging scrap, according to claim 1 , to charge scrap in a crucible of a vacuum-melting apparatus, said scrap being bound with a wire; the device comprising

- a first tubular body defining a vertical axis;

- a second tubular body arranged coaxially inside or outside said first tubular body;

- first actuating means adapted to translate the first tubular body and the second tubular body along said vertical axis;

- second actuating means adapted to rotate the second tubular body with respect to the first tubular body or vice-versa, about said vertical axis; wherein the lower end of the wall of the first tubular body has at least one opening shaped so that said lower end has at least one protrusion along said at least one opening, so that the wire which bounds the scrap can pass through said at least one opening and be suspended on said at least one protrusion; wherein the lower end of the wall of the second tubular body has at least one opening; wherein the device, according to the angular position of the second tubular body with respect the first tubular body, can take a loading position which allows to pass the wire through said at least one opening of the first tubular body and through said at least one opening of the second tubular body, and which allows to suspend the wire on said at least one protrusion; and wherein said second tubular body or said first tubular body is adapted to be rotated, in a first direction of rotation, from said loading position to a locking position, wherein the wall of the second tubular body at least partially obstructs the opening of the first tubular body so as to prevent the wire suspended on the protrusion from leaving said at least one protrusion; and is adapted to be rotated in a second direction of rotation, opposite to the first direction of rotation, from said locking position to a release position allowing the release of the wire from said at least one protrusion.

Advantageously, the device allows to release scrap, or more generally the charging material, in a controlled and precise manner.

Advantageously, the first tubular body and the second tubular body can be lowered towards the crucible, so that the suspended scrap is arranged within the crucible, at the desired predetermined position, e.g. on the bottom of the crucible. Therefore, splashes and damages to the crucible are avoided, regardless of the liquid level in crucible.

The controlled release of scrap, in particular big scrap pieces, can be performed at a defined position and in a predetermined way, i.e. there is no waiting time until a rope is burnt or molten, as in the prior art.

It can be achieved a quick lowering and release of the scrap (no waiting time until a wire is burnt or molten), and therefore the cycle times are reduced.

It can be achieved a careful placing of scrap within the crucible, e.g. on the bottom of the crucible, without the free falling which occurs in the prior art.

Also, there is no chemical alteration of the crucible content due to an aluminum/tin wire which melts for scrap release. Indeed, advantageously, the device of the invention allows to use a wire made of a material which does not pollute the melt and/or which can substantially be an alloying material, such as for example a wire made of Nickel Chromium (e.g. 80-20).

Another advantage is that the device can be made with no actuating means within the melting chamber of a vacuum-melting apparatus, in particular with no actuating means within the crucible. In particular, said first actuating means and said second actuating means are outside the crucible, in particular also in the release position, when the suspended scrap is within the crucible and is released. This aspect is particularly advantageous because if actuating means are within the melting chamber, in particular within the crucible, their operation can be negatively affected by heat and/or electromagnetic fields, in particular when the crucible is induction heated.

Further advantages of the device are that:

- it can be used in any size of VIM furnaces or even other vacuum plants;

- it is simple and robust;

- allows the automation of many steps or even of the whole charging process; in particular, there is no need for operator interaction or observation between closing of the charging chamber and re-opening of charging chamber, thus the cycle times can be reduced, and the degree of attention of the operator can be reduced.

Another advantage is that the device can also be used to charge scrap, in particular small scrap, by means of a bucket, e.g. a bucket provided with openable bottom.

The device can also be used to perform other operations, such as sampling (e.g. with a lollipop probe); temperature measuring (e.g. with a temperature probe); and bridge breaking. Indeed, different tools can be coupled with the end(s), in particular lower end(s), of the first tubular body and/or of the second tubular body.

For example, in order to perform a bridge breaking operation, a bridge breaking tool can be coupled to the lower end(s) of the first tubular body and/or of the second tubular body in order to break the solidified material on top of the melt within the crucible. The pressure exerted by the telescopic system can be exploited for this purpose.

Further features and advantages of the invention will be more apparent in light of the detailed description of particular, but not exclusive, embodiments.

The term “scrap” means one or more metal parts or bodies. In particular, the term scrap means one or more parts or bodies rejected or discarded, useful as material for reprocessing.

With “vertical axis” it is in particular meant an axis which is orthogonal to the resting plane, in particular to the horizontal resting plane, of the apparatus comprising the scrap charging device according to the invention.

The invention also relates to a vacuum-melting apparatus according to claim 8.

The invention also relates to a method, according to claim 1 1 , for charging scrap into a crucible of a vacuum melting apparatus by means of a scrap charging device, said scrap being bound with a wire; the method comprising the steps of: a) providing the device in a loading position in which said at least one opening of the second tubular body allows the wire to pass through said at least one opening of the first tubular body; b) suspending the wire on said at least one protrusion; c) rotating the second tubular body or the first tubular body about said vertical axis in a first direction of rotation, from said loading position to a locking position in which the wall of the second tubular body obstructs at least partially the at least one opening of the first tubular body so as to prevent the wire suspended on the at least one protrusion from leaving said at least one protrusion; d) translate the first tubular body and the second tubular body along said vertical axis towards the crucible up to bring the scrap inside the crucible; e) rotate the second tubular body or the first tubular body about said vertical axis in a second direction of rotation, opposite to the first direction of rotation, from said locking position to a release position whereby the wire is released from said at least one protrusion.

The dependent claims describe particular embodiments of the invention.

Brief description of the drawings

The description is provided by way of a non-limiting example, referring to the accompanying drawings, also given by way of a non-limiting example, in which: Fig. 1 schematically shows a side section view of the device according to the invention, in a first configuration;

Fig. 1 A shows an enlarged detail of Fig. 1 ;

Fig. 2 schematically shows a side section view of the device of Fig. 1 in a second configuration;

Fig. 3 schematically shows a side section view of the device of Fig. 1 in a third configuration;

Fig. 4 schematically shows a side section view of the device of Fig. 1 in a fourth configuration;

Fig. 5 shows a perspective view of part of the device of Fig. 1 , in the loading position;

Fig. 6 shows a perspective view of the part of the device of Fig. 1 , in the locking position;

Fig. 7 shows a perspective view of the part of the device of Fig. 1 , in the release position;

Fig. 8 schematically shows a side section view of an apparatus according to the invention;

Fig. 9 shows a perspective view of part of the apparatus of Fig. 8;

Fig. 9A shows a perspective view of part of the device of Fig. 1 in the loading position (as in Fig. 5);

Fig. 10 schematically shows a side section view of part of the apparatus of Fig. 8, when the device according to the invention is in the configuration of Fig. 3;

Fig. 1 1 shows a perspective view of part of the device according to the invention and of a component usable with such device.

The same reference numerals in the drawings identify the same elements or components.

Detailed description of embodiments of the invention

With reference to the figures, embodiments of a scrap charging device 80 are described.

The scrap charging device 80 is suitable for charging scrap 90, or other charging material, in a crucible 81 of a vacuum-melting apparatus 8. The scrap charging device 80 is particularly, but not exclusively, suitable for charging scrap 90 which is bound with a wire 9. In particular, the wire 9 forms a loop 91 (Fig. 10) which can be suspended on one or more protrusions 12a, 12b of the scrap charging device 80, as it will be described more in details.

The scrap charging device 80, also referred to as device 80, is particularly suitable for an induction vacuum melting apparatus 8, which comprises an induction heated crucible 81.

By way of non-limiting example, the device 80 will be described with reference to an induction vacuum melting apparatus 8.

In all the embodiments, the device 80 comprises

- a first tubular body 1 defining a vertical axis Y;

- a second tubular body 2 arranged coaxially inside or outside said first tubular body 1 ;

- first actuating means 41 adapted to translate the first tubular body 1 and the second tubular body 2 along said vertical axis Y;

- second actuating means 42 adapted to rotate the second tubular body 2 with respect to the first tubular body 1 or vice-versa (/.e. adapted to rotate the first tubular body 1 with respect to the second tubular body 2) about said vertical axis Y; wherein the lower end 19 of the wall 10 of the first tubular body 1 has at least one opening 1 1 a, 1 1 b shaped so that said lower end 19 has at least one protrusion 12a, 12b, in particular along said at least one opening 1 1 a, 1 1 b, so that the wire 9 which binds the scrap 90 can pass through said at least one opening 1 1 a, 1 1 b and be suspended on said at least one protrusion 12a, 12b; wherein the lower end 29 of the wall 20 of the second tubular body 2 has at least one opening 21 a, 21 b; wherein the device 80, according to the angular position of the second tubular body 2 with respect the first tubular body 1 , can take a loading position (Fig. 5) which allows to pass the wire 9 through said at least one opening 1 1 a, 1 1 b of the first tubular body 1 and through said at least one opening 21 a, 21 b of the second tubular body 2, and which allows to suspend the wire 9 on said at least one protrusion 12a, 12b; and wherein said second tubular body 2 or said first tubular body 1 is adapted to be rotated, in a first direction of rotation (e.g. a clockwise rotation for example of said second tubular body 2), from said loading position (Fig. 5) to a locking position (Fig. 6), in which the wall 20 of the second tubular body 2 at least partially, preferably partially, obstructs the opening 11 a, 11 b of the first tubular body 1 so as to prevent the wire 9 suspended on the protrusion 12a, 12b from leaving said at least one protrusion 12a, 12b; and is adapted to be rotated in a second direction of rotation (e.g. a counter-clockwise for example of said second tubular body 2), opposite to the first direction of rotation, from said locking position (Fig. 6) to a release position (Fig. 7) allowing the release of the wire 9 from said at least one protrusion 12a, 12b.

In particular, the device 80 is advantageously configured so that, during the rotation of the second tubular body 2 or of the first tubular body 1 in the second direction of rotation, the wire 9 which is suspended on the at least one protrusion 12a, 12b is pushed by the wall 20 of the second tubular body 2 to be released from said at least one protrusion 12a, 12b.

To this end, for example, the distance between the wall 10 of the first tubular body 1 and the wall 20 of the second tubular body 2 is preferably from 0,2 to 8 mm.

Said distance is, in particular, the radial distance along a direction perpendicular to the vertical axis Y, or in other words said distance is the radial gap between the first tubular body 1 and the second tubular body 2.

The first tubular body 1 and the second tubular body 2, in particular, extend about the same vertical axis Y.

It is particularly preferred that the second tubular body 2 is arranged coaxially inside the first tubular body 1 , and that the second actuating means 42 are adapted to rotate the second tubular body 2 with respect to the first tubular body 1 (as shown in Figures e.g. 1 -4). The construction of the device 80 is thereby simpler. Alternatively, the second tubular body 2 is arranged coaxially inside the first tubular body 1 and the second actuating means 42 are adapted to rotate the first tubular body 1 with respect to the second tubular body 2; or alternatively the first tubular body 1 is arranged coaxially inside the second tubular body 2 and the second actuating means 42 are adapted to rotate the second tubular body 2 with respect to the first tubular body 1 ; or alternatively the first tubular body 1 is arranged coaxially inside the second tubular body 2 and the second actuating means 42 are adapted to rotate the first tubular body 1 with respect to the second tubular body 2.

Figures 5, 6 and 7 are also representative of the variant wherein the second tubular body 2 is arranged coaxially inside the first tubular body 1 and the second actuating means 42 are adapted to rotate the first tubular body 1 with respect to the second tubular body 2. In order to pass from the loading position (Fig. 5) to the locking position (Fig. 6), the first tubular body 1 is rotated e.g. counter-clockwise; and in order to pass from the locking position (Fig. 6) to the release position (Fig. 7), the first tubular body 1 is rotated e.g. clockwise.

Advantageously, the device 80 comprises a telescopic system comprising the first tubular body 1 and the second tubular body 2. In particular, the first tubular body 1 and the second tubular body 2 are a movable part, or the movable part, of the telescopic system. The telescopic system, in particular, also comprises a third tubular body 3, which is fixed in position.

The first tubular body 1 and the second tubular body 2 are arranged within the third tubular body 3 and are adapted to translate, in particular integrally with each other, along said vertical axis Y with respect to the third tubular body 3 by means of said first actuation means 41 .

In particular, the first tubular body 1 and the second tubular body 2 can move from a retracted position (e.g. Fig. 1 , Fig, 2 and Fig. 4), or upper position, to an extended position (e.g. Fig. 3), or lower position, and vice-versa.

In the retracted position, the lower end 19 of the first tubular body 1 and the lower end 29 of the second tubular body 2 are within the charging chamber 82 of the apparatus 8, and therefore outside the melting chamber 83. In the retracted position, the device 80 is in the loading position and then, after the wire 9 has been suspended, the device 80 takes the locking position by rotating the first tubular body 1 or the second tubular body 2. In the example shown in the Figures, in the retracted position, the device 80 is in the loading position (Fig. 5); and then the second tubular body 2 is rotated so that the device 80 takes the locking position after the wire 9 has been suspended (Fig. 6).

In the extended position, the lower end 19 and the lower end 29 are within the melting chamber 83. Preferably, but not exclusively, in the extended position, the lower end 19 and the lower end 29 are outside the crucible 81 . In the extended position, the suspended scrap 90 is within the crucible 81 , preferably on the bottom of the crucible 81 , i.e. in contact with the bottom. The device 80 can pass from the locking position to the release position when the first tubular body 1 and the second tubular body 2 are in the extended position.

For example, the second tubular body 2 can be rotated so that the device 80 passes from the locking position to the release position when the first tubular body 1 and the second tubular body 2 are in the extended position.

Preferably, the first actuating means 41 , which preferably comprise one or more wheels, or racks, are coupled to the first tubular body 1 , in particular to the outer surface of the first tubular body 1 , whereby the first actuating means 41 can cause a translation of the first tubular body 1 along the vertical axis Y.

The first tubular body 1 and the second tubular body 2 are coupled to each other so that they can translate together along the vertical axis Y, and so that the second tubular body 2 can rotate about the vertical axis Y with respect to the first tubular body 1 .

The second actuating means 42 preferably comprise a motor, a rack and a pinion. Preferably, there is provided a shaft 421 (indicated in Fig. 1 and 1 A) inside the second tubular body 2. The shaft 421 is coupled to the second actuating means 42 and to the second tubular body 2, in particular so that the shaft 421 can transmit a rotation motion to the second tubular body 2.

The first tubular body 1 and the second tubular body 2 are, in particular, made of metal, for example steel.

The at least one opening 1 1 a, 1 1 b of the first tubular body 1 is in particular an opening of the lower edge 191 (indicated in Fig. 6) of the wall 10.

Preferably, part of the at least one opening 1 1 a, 1 1 b is delimited by the lateral surface 121 (Fig. 6) and by the upper surface 122 of said at least one protrusion 12a, 12b. Said lateral surface 121 is preferably vertical. Said upper surface 122 is preferably horizontal.

In particular, said at least one opening 21 a, 21 b of the second tubular body 2 extends along said vertical axis Y from the lower edge 291 of the second tubular body 2 up to above said at least one protrusion 12a, 12b of the first tubular body 1 . In particular, the at least one opening 21 a, 21 b extends above the upper surface 122 of said at least one protrusion 12a, 12b.

The at least one protrusion 12a, 12b is part of the wall 10 of the first tubular body 1 ; said wall 10 being preferably cylindrical. In other words, the at least one protrusion 12a ,12b is a cylindrical wall portion.

Preferably, said at least one opening 11 a, 1 1 b of the first tubular body 1 is shaped substantially like an upside-down letter “L”.

The first tubular body 1 preferably comprises two openings 11 a, 1 1 b opposite to each other, preferably diametrically opposite to each other, whereby the first tubular body 1 has two protrusions 12a, 12b to suspend the wire 9. This allows, in particular, a more stable suspension of the wire 9. The two protrusions 12a, 12b are preferably diametrically opposite to each other.

In this case, the second tubular body 2 comprises two openings 21 a, 21 b opposite to each other, preferably diametrically opposite to each other.

In particular, due to the openings 21 a, 21 b, the lower end 29 of the second tubular body 2 preferably is substantially formed by two cylindrical wall portions 22a, 22b. The wall 20 of the second tubular body 2 is preferably cylindrical.

With particular reference to Fig. 5, in the loading position, each opening 1 1 a, 11 b is preferably completely not obstructed by the wall 20 of the second tubular body 2.

With particular reference to Fig. 6, in the locking position, the wall 20 obstructs part of the each opening 1 1 a, 11 b, preferably so that only a part 1 1 1 (Fig. 6) of each opening 1 1 a, 1 1 b which is above the respective protrusion 12a, 12b is not obstructed by the wall 20. Thereby, the wall 20 prevents the wire 9 from leaving the protrusions 12a, 12b. Preferably, in the locking position, each protrusion 12a, 12b is partially flanked by the wall 20 of the second tubular body 2. More in details, each cylindrical wall portion 22b, 22a flanks a portion of a respective protrusion 12a, 12b.

With particular reference to Fig. 7, as already mentioned, when passing from the locking position to the release position, the wire 9 which is suspended on the protrusions 12a, 12b is pushed by the wall 20 of the second tubular body 2 to be released from the protrusions 12a, 12b.

In the release position, preferably, the part 1 11 of each opening 1 1 a, 1 1 b which is above the respective protrusion 12a, 12b is obstructed by the wall 20, in particular by a respective cylindrical wall portion 22a, 22b. Instead, preferably, the remainder part of each opening 1 1 a, 1 1 b is not obstructed by the wall 20. Preferably, in the release position, the protrusions 12a, 12b are completely flanked by the wall 20, in particular by a respective cylindrical wall portion 22a, 22b.

The invention also relates to a vacuum-melting apparatus 8 provided with at least one scrap charging device 80, e.g. with one scrap charging device 80.

The apparatus 8 preferably, but not exclusively, is a vacuum-induction-melting apparatus.

With particular reference to Fig. 8 and Fig. 9, the apparatus 8 preferably comprises

- a scrap charging chamber 82;

- a melting chamber 83 provided with a crucible 81 and preferably with at least one mold 84; in particular, the crucible 81 , and optionally the at least one mold 84, are arranged within the melting chamber 83; in particular for bigger furnaces, the mold(s) can be arranged in a separate casting chamber which is located next to the melting chamber, the casting chamber and the melting chamber being separated by a vacuum valve gate;

- a vacuum valve gate 85, which can be opened and closed, arranged between said scrap charging chamber 82 and said melting chamber 83.

The apparatus 8 is configured so that the lower end 19 of the first tubular body 1 and the lower end 29 of the second tubular body 2 can translate from the scrap charging chamber 82 to the melting chamber 83, and vice-versa.

The scrap charging device 80 and the charging chamber 82 are preferably coupled to each other. For example, the third body 3 can be coupled to the charging chamber 82, e.g. to a wall of the charging chamber 82.

The scrap charging chamber 82 is preferably part of the scrap charging device 80.

Preferably, said first actuation means 41 and said second actuation means 42 are advantageously arranged outside, preferably completely and always outside, said melting chamber 83; and more preferably also outside the crucible 81 . Thereby, advantageously, the operation of the first actuation means 41 and of the second actuation means 42 is not negatively affected by, for example, heat, vacuum and/or electromagnetic fields.

The scrap charging chamber 82 is provided with a door 821 which can be opened and closed to open and close the scrap charging chamber 82.

The apparatus 8 also comprises a vacuum pump 86 connected to the charging chamber 82 to decrease the pressure inside the charging chamber 82, i.e. to evacuate the charging chamber 82.

In particular, the charging chamber 82 is at atmospheric pressure during scrap 90 loading, and is evacuated, i.e. is brought to a pressure lower than atmospheric pressure, before the vacuum valve gate 85 opening.

The apparatus 8 also comprises a vacuum pump 87, or main vacuum pump 87, connected to the melting chamber 83 to decrease the pressure inside the melting chamber 83.

In particular, the vacuum valve gate 85 is opened when both the charging chamber 82 and the melting chamber 83 are under vacuum.

The crucible 81 , as mentioned, is preferably induction heated. In particular, the crucible 81 is provided with one or more induction coils 81 1 .

In particular, the crucible 81 is vertical during melting and scrap charging, and is tiltable for casting molten metal into the at least one mold 84.

In particular, casting is performed under vacuum through a tundish 88 or directly from the crucible 81 into the one or more molds 84.

Preferably, there is provided a plurality of molds 84 where the molten metal which is in the crucible 81 can be cast. Preferably, the plurality of molds 84 is mounted on a rotatable table 841 .

The invention also relates to a method for charging (in particular back- charging) scrap 90, into a crucible 81 of a vacuum melting apparatus 8 by means of a scrap charging device 80, said scrap 90 being bound with a wire 9, in particular forming a loop 91 ; the method comprising the steps of: a) providing the device 80 in a loading position (Fig. 5) in which said at least one opening 21 a, 21 b of the second tubular body 2 allows the wire 9 to pass through said at least one opening 11 a, 1 1 b of the first tubular body 1 ; b) suspending the wire 9 on said at least one protrusion 12a, 12b; c) rotating the second tubular body 2 or the first tubular body 1 about said vertical axis Y in a first direction of rotation, from said loading position (Fig. 5) to a locking position (Fig. 6) in which the wall 20 of the second tubular body 2 obstructs at least partially, preferably partially (in particular only partially), the at least one opening 11 a, 1 1 b of the first tubular body 1 so as to prevent the wire 9 suspended on the at least one protrusion 12a, 12b from leaving said at least one protrusion 12a, 12b; d) translate the first tubular body 1 and the second tubular body 2 along said vertical axis Y towards the crucible 81 up to bring the scrap 90 inside the crucible 81 ; e) rotate the second tubular body 2 or the first tubular body 1 about said vertical axis Y in a second direction of rotation, opposite to the first direction of rotation, from said locking position (Fig. 6) to a release position (Fig. 7) whereby the wire 9 is released from said at least one protrusion 12a, 12b.

In particular, in steps a), b) and c), the lower end 19 of the first tubular body 1 and the lower end 29 of the second tubular body 2 are inside the scrap charging chamber 82 of said vacuum melting apparatus 8.

In particular, during step d), the lower end 19 and the lower end 29 are brought inside the melting chamber 83. Preferably, but not exclusively, during step d) the scrap 90 is brought on the bottom 812 of the crucible 81 , i.e. in contact with the bottom 812 of the crucible 81 ; this is advantageously made possible by the device 80.

During step e), in particular, the lower end 19 and the lower end 29 are in the melting chamber 83, preferably outside the crucible 81 .

As already mentioned, during step e) the wire 9 is pushed by the wall 20 of the second tubular body 2 to be released from said at least one protrusion 12a, 12b.

When two protrusions 12a, 12b are provided, the wall 20 pushes the wire 9, in particular the same wire 9, until it is released from the protrusions 12a, 12b.

After step e), the lower end 19 and the lower end 29 are brought again within the charging chamber 82, and the second tubular body 2, or the first tubular body 1 , is rotated to the loading position of the device 80, so that another wire 9 can be suspended to the one or more protrusions 12a, 12b, starting from step a).

By way of non-limiting example, an example of charging sequence is described below, starting from a condition wherein the vacuum valve gate 85 is open, the charging chamber 82 is under vacuum and the door 821 is closed (Fig. 1 )- Then, e.g. by pressing a button, the vacuum valve gate 85 closes, the charging chamber 82 is flooded with air, and the door 821 opens. The device 80 is in the loading position, and the wire 9 which binds the scrap 90 is suspended on the protrusions 12a, 12b (Fig. 2).

Then, e.g. by pressing a button, the second tubular body 2 (for example) rotates so that the device 80 passes to the locking position), the door 821 closes, the charging chamber 82 is evacuated, the vacuum valve gate 85 opens and the first tubular body 1 and second tubular body 2 are translated in the extended position, to bring the suspended scrap 90 at the desired position within the crucible 81 (Fig. 3).

Then, the device 80 is moved to the release position (e.g. rotating the second tubular body 2) to release the suspended wire 9, and thus the scrap 90, in the crucible 81 ; the first tubular body 1 and the second tubular body 2 are translated upwards, in the retracted position, and the second tubular body 2 is rotated so that the device 80 passes to the loading position (Fig. 4).

The apparatus 8 can optionally comprise an automation system, to automate one or more steps of the method. The above-mentioned buttons are for example part of such automation system.

Optionally, the apparatus may comprise a carriage 89 (Figs. 1 -4) where one or more clusters of scrap 90, each bound with a respective wire 9, are arranged. The carriage 89 can, for example, slide on a rail.

With particular reference to Fig. 1 1 , the device 80 is also suitable to charge scrap contained in a bucket 92. Indeed, instead of the wire 9, the handle 93 of the bucket 92 can be suspended to the one or more protrusions 12a, 12b. The bucket 92 can be, for example, provided with portions 94 hinged to the wall of the bucket 92. Such portions 94 are for example bound with a self-burning rope or aluminum/tin wire in a closed position, to form a closed bottom of the bucket 92. The rope or wire can burn or melt to open the bottom, as shown in Fig. 1 1 , whereby the scrap is released in the crucible. In other words, a bucket with an orange peel design can be suspended on the protrusions 12a, 12b.

Claims

1. Scrap charging device (80) to charge scrap (90) in a crucible (81 ) of a vacuummelting apparatus (8), said scrap (90) being bound with a wire (9); the device (80) comprising

- a first tubular body (1 ) defining a vertical axis (Y);

- a second tubular body (2) arranged coaxially inside or outside said first tubular body (1 );

- first actuating means (41 ) adapted to translate the first tubular body (1 ) and the second tubular body (2) along said vertical axis (Y);

- second actuating means (42) adapted to rotate the second tubular body (2) with respect to the first tubular body (1 ) or vice-versa, about said vertical axis (Y); wherein the lower end (19) of the wall (10) of the first tubular body (1 ) has at least one opening (1 1 a, 1 1 b) shaped so that said lower end (19) has at least one protrusion (12a, 12b) along said at least one opening (1 1 a, 1 1 b), so that the wire (9) which bounds the scrap (90) can pass through said at least one opening (11 a, 1 1 b) and be suspended on said at least one protrusion (12a, 12b); wherein the lower end (29) of the wall (20) of the second tubular body (2) has at least one opening (21 a, 21 b); wherein the device (80), according to the angular position of the second tubular body (2) with respect the first tubular body (1 ), can take a loading position which allows to pass the wire (9) through said at least one opening (1 1 a, 1 1 b) of the first tubular body (1 ) and through said at least one opening (21 a, 21 b) of the second tubular body (2), and which allows to suspend the wire (9) on said at least one protrusion (12a, 12b); and wherein said second tubular body (2) or said first tubular body (1 ) is adapted to be rotated, in a first direction of rotation, from said loading position to a locking position, wherein the wall (20) of the second tubular body (2) at least partially obstructs the opening (1 1 a, 1 1 b) of the first tubular body (1 ) so as to prevent the wire (9) suspended on the protrusion (12a, 12b) from leaving said at least one protrusion (12a, 12b); and is adapted to be rotated in a second direction of rotation, opposite to the first direction of rotation, from said locking position to a release position allowing the release of the wire (9) from said at least one protrusion (12a,

2. Device (80) according to claim 1 , comprising a telescopic system comprising the first tubular body (1 ), the second tubular body (2) and a third tubular body (3), the third tubular body (3) being fixed in position; wherein the first tubular body (1 ) and the second tubular body (2) are arranged within the third tubular body (3) and are adapted to translate, in particular integrally with each other, along said vertical axis (Y) with respect to the third tubular body (3) by means of said first actuation means (41 ).

3. Device (80) according to any one of the preceding claims, wherein said at least one opening (21 a, 21 b) of the second tubular body (2) extends along said vertical axis (Y) from the lower edge (291 ) of the second tubular body (2) up to above said at least one protrusion (12a, 12b) of the first tubular body (1 ).

4. Device (80) according to any of the preceding claims, wherein said at least one protrusion (12a, 12b) is part of the wall (10) of the first tubular body (1 ); said wall (10) being preferably cylindrical.

5. Device (80) according to any one of the preceding claims, wherein said at least one opening (1 1 a, 1 1 b) of the first tubular body (1 ) is shaped substantially like an upside-down letter “L”.

6. Device (80) according to any one of the preceding claims, wherein the first tubular body (1 ) comprises two openings (1 1 a, 1 1 b) opposite to each other, preferably diametrically opposite to each other, whereby the first tubular body (1 ) has two protrusions (12a, 12b), preferably diametrically opposite to each other, to suspend the wire (9).

7. Device (80) according to claim 6, wherein the second tubular body (2) comprises two openings (21 a, 21 b) opposite to each other, preferably diametrically opposite to each other.

8. Vacuum-melting apparatus (8), in particular vacuum-induction-melting apparatus, provided with at least one scrap charging device (80) according to anyone of the preceding claims.

9. Apparatus (8) according to claim 8, comprising

- a scrap charging chamber (82);

- a melting chamber (83) provided with a crucible (81 ); - a vacuum valve gate (85) arranged between said scrap charging chamber (82) and said melting chamber (83); wherein the lower end (19) of the first tubular body (1 ) and the lower end (29) of the second tubular body (2) can translate from the scrap charging chamber (82) to the melting chamber (83), and vice-versa; preferably wherein the melting chamber (83) is provided with at least one mold (84), or wherein at least one mold is placed in a casting chamber of the apparatus.

10. Apparatus (8) according to claim 8 or 9, wherein said first actuation means (41 ) and said second actuation means (42) are arranged outside, preferably completely outside, said melting chamber (83).

11. Method for charging scrap (90) into a crucible (81 ) of a vacuum melting apparatus (8) by means of a scrap charging device (80) according to any one of claims 1 to 7, said scrap (90) being bound with a wire (9); the method comprising the steps of: a) providing the device (80) in a loading position in which said at least one opening (21 a, 21 b) of the second tubular body (2) allows the wire (9) to pass through said at least one opening (1 1 a, 1 1 b ) of the first tubular body (1 ); b) suspending the wire (9) on said at least one protrusion (12a, 12b); c) rotating the second tubular body (2) or the first tubular body (1 ) about said vertical axis (Y) in a first direction of rotation, from said loading position to a locking position in which the wall (20) of the second tubular body (2) obstructs at least partially the at least one opening (1 1 a, 1 1 b) of the first tubular body (1 ) so as to prevent the wire (9) suspended on the at least one protrusion (12a, 12b) from leaving said at least one protrusion (12a, 12b); d) translate the first tubular body (1 ) and the second tubular body (2) along said vertical axis (Y) towards the crucible (81 ) up to bring the scrap (90) inside the crucible (81 ); e) rotate the second tubular body (2) or the first tubular body (1 ) about said vertical axis (Y) in a second direction of rotation, opposite to the first direction of rotation, from said locking position to a release position whereby the wire (9) is released from said at least one protrusion (12a, 12b).

12. Method according to claim 11 , wherein in steps a), b) and c), the lower end (19) of the first tubular body (1 ) and the lower end (29) of the second tubular body (2) are inside the scrap charging chamber (82) of said vacuum melting apparatus (8).

13. Method according to claim 11 or 12, wherein during step e) the wire (9) is pushed by the wall (20) of the second tubular body (2) to be released from said at least one protrusion (12a, 12b).