GB2049510A

GB2049510A - Electroslag casting mould

Info

Publication number: GB2049510A
Application number: GB7917947A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-05-14
Filing date: 1979-05-23
Publication date: 1980-12-31
Also published as: DE2920202C2; SE416897B; GB2049510B; AT362537B; SE7904208L; FR2459092B1; JPS55161563A; DE2920202A1; JPS5738341B2; ATA359179A; FR2459092A1

Abstract

The mould has a wall of hollow tubular metal bars 1, the lateral external surfaces of some of the bars being provided with longitudinal grooves 4, preferably defined by an arcuated surface having a radius substantially equal to that of the lateral surface of the round bar in contact with the groove. The bars are arranged longitudinally, adjoin closely one another and are provided with transversal grooves for receiving bands 5 which encompass said bars. <IMAGE>

Description

SPECIFICATION Mould for electroslag remelting of metal ingots The invention relates to electrometallurgy, in particular, to mould assemblies intended to form ingots or castings in electroslag remelting of metals or remelting of consumable electrodes by any alternative technique and in casting of molten metal.

The invention can be advantageously employed in electroslag metal remelting plants and in electroslag metal casting processes.

There are known moulds for forming metal ingots or castings, comprising cooled vertical walls defining a cavity filled with molten metal. At the bottom, the cavity is closed by a bottom plate. Such moulds have found a wide application in plants for electroslag remelting of metal.

The main object of the invention is to provide a mould for electroslag remelting of metal ingots which would raise plant efficiency.

Another important object of the invention is to improve the quality of melted ingots through the use of the mould of the invention.

A major object of the invention is to provide a mould whose assembly/disassembly would require considerably less time than that for the known moulds.

Still another object of the invention is to provide a mould with a lesser number of component parts, i.e., one of a simpler design, while enhancing its radial rigidity, and, in consequence, its service reliability.

This invention provides a mould for remelting metal ingots, comprising hollow metallic bars of tubular shape, arranged lengthwise, adjoining one another and forming a mould assembly wall encompassed by bands, according to the invention, at least one half of the bars having on their external surfaces at places of contact with lateral surfaces of adjacent hollow metallic bars at least one longitudinal groove of uniform depth defined by an arcuated surface.

The provision of said grooves makes it possible to substitute the contact along a line between the adjacent bars by a contact along a surface and so ensure a close attachment of the adjacent bars on assembly. This prevents the leakage of molten metal and slag past the wall of the mould cavity and, thus, improves the surface quality of resulting ingots and increases the yield of standard metal and also results in a speedier assembly-disassembly of the mould to minimize idle time between heats and so enhance plant efficiency.

Each hollow metallic bar is preferably provided with a groove, the radius of the arcuated surface thereof being substantially equal to that of the external surface of the bar bearing upon it.

A groove so shaped causes surfaces of the adjacent bars to bear tightly one against the other and provides a greatest radial rigidity of the assem bled mould wall and prevents leakage of molten metal or slag out of the mould cavity.

Each of the hollow metallic bars may have at least two longitudinal grooves of unequal depths.

This makes it possible to change the shape and the corrugations of the surface of the ingots, this, in turn, having a substantial effect upon the cooling conditions and, thus, upon the process of solidification.

For example, a greater number of corrugations of the mould internal surface increases the area of contact of the surface with the ingot being formed and so enhances the cooling of the ingot. Because of a more intensive cooling, a slag crust is more effectively confined to the surface of the internal wall of the mould assembly, this, in turn, minimizes the risk of a breakout of molten metal pastthe mould wall and of defects appearing on the ingot surface.

The design of the mould according to the invention makes it possible, while using a same number of the hollow metallic bars with the joining lateral grooves of different depths, to produce ingots of various cross sectional areas.

The hollow metallic bars may be oval in cross section, it then being expedient to provide the groove at least on one of the rounded sides.

This minimizes the number of the bars necessary to build up a mould, more particularly, when melting ingots of large cross sections, and additionally reduces the time for fitting the mould assembly together, thus enhancing plant efficiency.

Each hollow metallic bar may be provided with at least one additional longitudinal duct for the passage of a coolant.

The provision of the additional duct, preferably for oval-shaped bars, improves the cooling of the mould wall, also permitting the ingot solidification process to proceed at a higher rate.

It is advantageous to place a pipe, connected to a cooling system, into the cavity and/or the duct of each metallic bar in a manner to keep the pipe clear of the wall of said metallic bar.

This brings down the consumption of the coolant, while ensuring optimum conditions for the cooling of the mould wall because of a greater velocity of flow of the coolant.

It is good practice to provide at the bottom end of the pipe, on the ingot-forming side of the hollow metallic bar wall, an orifice which brings the interior of said pipe in communication with the interior of the bar or the duct in the bar where such pipe is located.

The orifice in the bottom part of the pipe induces a flow of coolant directed at the most thermally stressed part of the mould and, thus, improves the cooling of the mould wall in the most dangerous zone.

The pipe should preferably be placed at a distance from the ingot-forming wall of the hollow metallic bar so as to bring it in contact with the opposite wall of said bar.

This is sure to improve the cooling of the ingotforming wall of the bar and thus to enhance the service reliability of the mould because of a sufficiently high velocity of the coolant flow.

It is desirable to divide the space between the pipe and the wall of the hollow metallic bar by vertical partitions, and to arrange the latter in a plane passing through the longitudinal centre lines of the hollow metallic bar and of the arcuated surface of the longitudinal groove.

The partitions make it possible to supply the coolant only on the side of the bar forming wall and, therefore, to reduce, by almost one half, the consumption of the coolant.

The pipe may be offset with respect to the longitudinal centre line of the hollow metallic bar toward the ingot-forming wall of the latter.

This reduces the cross sectional area of the passage by the ingot-forming wall of the bar and so increases the velocity of flow of the coolant and improves the cooling of both the ingot and the mould assembly wall.

It is advisable to provide, on the external side of each hollow metallic bar, at least one groove for a band to encompass the mould wall.

The band may then be located directly on the mould wall, this dispensing with the need for a mould assembly housing, simplifying the design of and lowering the requirements in metal for manufac turing the mould assemblies and, additionally, great ly reducing the mounting and demounting time thereof.

A header for distributing the coolant may be secured to said band.

Such mould construction simplifies the cooling system through elimination of a great many inlet and outlet branch pipes, enhances the service reliability of the mould, brings down the cost of the manufacture thereof, minimizes running expenses and facilitates maintenance.

The band is advantageously provided with the interior passage for the flow of coolant therethrough.

The provision of the interior passage in the band obviates the need for a header required to distribute the coolant among the hollow metallic bars making up the mould assembly wall. In addition, the service reliability of the mould assembly will be improved, and the requirements in metal for the manufacture thereof will be decreased.

These and other objects and features of the invention become readily apparent from one embodiment thereof which will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 represents a longitudinal section by a vertical plane of a mould assembly for melting and forming metallic ingots; Figure 2 is a top view of a mould assembly with a partial section for illustrating the contact of a tubular bar with another bar having two longitudinal grooves on the external lateral surface thereof; Figure 3 is an enlarged scale cross sectional view of a bar of tubular shape; Figure 4 is an enlarged cross sectional view of a bar, according to the invention, with two longitudinal external grooves on the lateral surface thereof;; Figure 5 is a top view of a mould assembly, wherein all the bars are provided with a single longitudinal groove, the radius of the arcuated surface thereof equalling that of the surface of the adjacent bars in contact with said bars; Figure 6 is cross sectional view of a mould assembly for obtaining ingots of square cross sections; Figure 7 is a cross sectional view of a mould assembly for obtaining ingots of rectangular cross sections; Figure 8 is a cross sectional view of a mould assembly for obtaining ingots of cruciform cross sections; Figure 9 is an enlarged scale cross sectional view of a bar having several grooves of different depths; Figure 10 is a longitudinal section view of a mould assembly with bars having grooves of different depths; Figure 11 is a cross sectional view of the mould assembly shown in Figure 10;; Figure 12 is an enlarged scale oval cross sectional view of a bar having an additional duct for the flow of a coolant; Figure 13 is a longitudinal section view of a mould assembly built of bars having an oval cross sectional shape; Figure 14 is a top view with a partial cross section of the mould assembly illustrated in Figure 13; Figure 15 is an enlarged scale cross sectional view of a bar whose cavity accommodates a pipe; Figure 16 is an enlarged scale broken cross sectional view of a bar enclosing a pipe; Figure 17 is an enlarged scale broken longitudinal section view of the bar with a pipe which is in contact with the non-ingot-forming wall of the bar; Figure 18 is an enlarged scale cross sectional view at XVIII-XVIII of the bar with pipe illustrated in Figure 17;; Figure 19 is an enlarged scale cross sectional view of a barwith a pipe and partitions; Figure 20 is an enlarged scale longitudinal section view of the bar with transversal grooves illustrated in Figure 19; Figure 21 is an enlarged scale cross sectional view of a bar with a pipe offset toward the ingot-forming wall; Figure 22 is an enlarged scale cross sectional view of a pipe arranged along the longitudinal centre line showing a transversal groove for a band; Figure 23 is a longitudinal section view of a mould assembly, according to the invention, with bands and a header; Figure 24 is an enlarged scale view of the subassembly A of Figure 23; Figure 25 is an enlarged scale cross sectional view of a band with cavities for the flow of a coolant.

Referring now to the drawings, there is shown therein a mould for electroslag remelting of metal ingots, which has a vertical cooled wall 1 (Figures 1 and 2) formed with hollow metallic bars 2 (Figure 3) of tubular shape, arranged lengthwise and adjoining the hollow metallic bars 3 (Figure 4) having on their external surfaces at least one longitudinal groove 4 of uniform depth defined by an arcuated surface of radius (R). The radii (R) of the external surfaces of the bars 2 (Figure 3) and 3 (Figure 4) and of the grooves 4 are equal to one another.

On its external side, the wall 1 (Figures 1 and 2) of the mould is enclosed in bands 5 which may be fixed to a housing 6, as in known designs of mould assemblies. In the mould of the invention, the housing may be dispensed with, as shown in Figure 2.

The radial rigidity of the wall 1 of the mould assembly is achieved by that each of at least one half of the hollow metallic bars 3 (Figure 4) is provided on their external lateral surfaces with at least one longitudinal groove;4 of uniform depth, defined by an arcuated surface. When the round bars 2 (Figure 3) with no grooves are used in combination with the bars 3 (Figure 4) having the longitudinal grooves 4, the bars are alternated, as shown in Figure 2, so that the grooves 4 of the bars 3 accommodate the lateral surfaces of the adjacent round bars 2 having no grooves.

The wall 1 (Figure 5) of the mould may consist of only the hollow metallic bars 3, of which each is provided with one longitudinal lateral groove 4.

Depending on the required shape of the ingot cross section, the hollow metallic bars 3 may be arranged along a circumference, as shown in Figure 5. To obtain ingots of square, rectangular or cruciform cross sections, the bars 3 are arranged as shown in Figures 6,7 and 8.

As is readily apparent from Figures 2, 5, 6,7 and 8, each hollow metallic bar 3 is provided with a groove 4, the radius (R) of the arcuated surface thereof being substantially equal to the radius of the external surface of the adjacent bar whose lateral surfaces engage said grooves 4.

In an alternative mould embodiment, each of the hollow metallic bars 7 (Figure 9) may have the grooves 4 of different depths (E Rand At1), but of a same radius (R) of the arcuated surface of the groove 4.

The longitudinal section of the mould will then be as shown in Figure 10, and the cross section, as illustrated in Figure 11. This mould has no housing, and the wall of the mould assembly is encompassed with the bands 5. In one of the alternative embodi ments, the mould may be built of hollow metallic bars 8 (Figure 12), oval is cross section, the groove 4 being provided at least on one of the rounded sides of the bars.

The hollow metallic bar 8 may have at least one additional duct 9 for the flow of a coolant along said bar, the mould assembly then being shaped as illustrated in Figures 13 and 14, and the wall 1 of the mould being built of a lesser number of the oval hollow metallic bars as compared to that of a round cross section.

The pipe 12 (Figure 16), connected to a cooling system, is placed inside the cavity 10 (Figure 15) of the bar 3 with a gap 11 with respect to the mould wall. The bottom end of the pipe 12 is provided, on the ingot-forming side of the wall of the bar 3, with an orifice 13, which communicates a cavity 14 of the pipe 12 with the cavity 10 of the bar 3.

Alternatively, the pipe 12 can be placed inside the duct 9 (Figures 12 and 14) of the bar 8, and the cavity 14 (Figure 16) of said pipe 12 communicating then with the duct 9 (Figure 12) inside the bar 8 (not shown).

To improve the cooling of the ingot-forming wall 15 (Figure 16) ofthe bar3through high-velocity flow of a coolant, the pipe 12 (Figures 17 and 18), in one of the embodiments, may be placed not by the ingotforming wall 15 of the hollow metallic bar 3, but in contact with the opposite internal non-ingot-forming wall l6ofsaid bar3.

Vertical partitions 17, located in the plane passing through the longitudinal centre lines of the hollow metallic bar 3 and the arcuated surface of the longitudinal groove 4, are placed in the gap 11 (Figures 19 and 20) between the pipe 12 and the wall of the hollow metallic bar 3.

In one of the alternative embodiments, the pipe 12 (Figure 21), is offset with respect to the longitudinal centre line of the hollow metallic bar 3 toward the mould ingot-forming wall 15.

The external side of each hollow metallic bar 3 (Figure 22) is provided with at least one transversal groove 18 for receiving the band 5 (Figure 23), which encompasses the wall 1 of the mould assembly. The band 5 (Figure 24) may accommodate a header 19 (Figure 23) for distributing a coolant. A band 20 (Figure 25) may be provided with a cavity 21 for the flow of a coolant.

The mould according to the invention is utilized in the manner below. The hollow metallic bars 2 and 3 (Figures 1 and 2) are built around a template, whose shape is that of an ingot to be melted, to form the mould wall 1. The ingot-forming surfaces of the walls 15 (Figure 23) of the hollow metallic bars 3 form the multifaceted internal mould assembly wall 1. This configuration improves not only the surface quality of ingots, but also their internal structure owing to an extended zone of variously oriented crystals. The external surface of the mould wall 1 is encompassed by the bands 5 which are, substantial liy, the mould second (after the bars) most important component part.The longitudinal uniform-depth grooves 4 (Figure 4) on the surface of the bar 3, defined by an arcuated surface, improve the surface quality of melted ingots as leakage of slag and metal is eliminated. When the radius (R) of the arcuated surface of the groove 4 of the bar 3 (Figures 5,6,7 and 8) is practically equal to the radius of the surface of another bar in contact with said bar 3, the surface quality of the melted ingot will be particularly high, as then no leakage of slag and metal virtually occurs through the surfaces of contact of the bars 3. To save costly materials, the mould may be built of the bars 3 (Figure 2) having two longitudinal grooves 4 each and of the round bars 2 without the grooves 4. It is advantageous to use the bars 7 (Figures 9, 10 and 11) with several grooves 4 of different depths.By variously combining the bars 7, it is possible to vary within a wide range not only the cross sectional shape of the melted ingot, but also the internal structure of the latter.

Metal ingots of rectangular cross sections, the so-called slab ingots with elongated side faces, are melted with the use of the bars 8 (Figures 12, 13 and 14) of oval cross section having the longitudinal grooves 4 on one of the rounded faces. This design of the bars 8 simplifies the mould operation and, in particular, reduces the time necessary for a change over from one type-size of ingot to another. In contrast to the known plane internal walls of mould assembly, the use of the oval bars 8 with the groove 4 for engagement by the lateral wall of another bar 8 makes the mould of the invention highly reliable and safe in service. When the oval bars 8 are employed, it is wise practice to provide an additonal duct therein.

Each duct then accommodates the pipe 12 (Figures 15 and 16) to improve the cooling of the mould. A flow of coolant in the cavity 10 of the bar 3 is directed toward the ingot-forming wall 15 (Figure 17) of the mould by the provision of the orifice 13 in the bottom part of the pipe 12. To enhance the effectiveness of cooling, the pipe 12 is offset from the longitudinal centre line of the bar 3 toward the wall 16 (Figures 17 and 18) facing the ingot-forming surface ofthewall 15 ofthe bar3 in a mannerto contact the surface of the wall 16 of the bar 3.

The flow of the coolant then washes only the working ingot-forming wall 15 of the bar 3. Further improvement in the cooling of the mould assembly may further be improved simultaneously with a reduction in the consumption of the coolant, by providing two vertical partitions 17 in the gap 11 (Figures 19 and 20) between the pipe 12 and the wall of the bar 3.

The coolant then actively flows only in the part of the gap 11 by the ingot-forming wall 15 of the bar 3.

Off-setting the pipe 12 (Figure 21 ) toward the ingot-forming surface of the wall 15 of the bar 3 considerably reduces the consumption of the cooling liquid.

High both strength and rigidity of the mould can be obtained by providing transversal grooves 18 on the outside of the bars 3 (Figure 22). These grooves 18 receive the bands 5 (Figures 23 and 24) which encompass the mould wall 1 and hold the bars 3 in a prescribed position. To save floorspace, the bands 5 carry the headers 19 connected to the mould cooling system. Further, the mould may be improved by providing a cavity 21 (Figure 25) for the flow of coolant inside the band 20, the latter also serving as a header.

The mould of the invention was tested by melting metal ingots of various shapes, inclusive mainly of round, square, rectangular, cruciform and even triangular cross section, the same number of the bars 3 having been used, as shown in the Figures 5, 6,7 and 8. The test heats have indicated that the quality of the ingots was very high. The ingots were easy to extract from the mould. The change in the shape of the mould cavity require only the use of the bands 5 of corresponding shape. Simplicity of design, high degree of unification and interchangeability of component parts of the mould concur to enhance the efficiency of metal ingot melting through lessertime required to build up the mould.

Claims

1. A mould for electroslag remelting of metal ingots comprising tubular hollow metallic bars, arranged lengthwise, adjoining one another and forming a mould wall encompassed with bands, one half at least of said bars at places of contact with the lateral surface of adjoining said hollow metallic bars is provided on the external lateral surfaces with at least one longitudinal groove of uniform depth defined by an arcuated surface.

2. A mould for electroslag remelting of metal ingots as claimed in claim 1, wherein each hollow metallic bar is provided with the groove, the radius of the arcuated surface thereof being substantially equal to the external surface of the bar which contacts said groove.

3. A mould for electroslag remelting of metal ingots as claimed in claim 2, wherein each of the hollow metallic bars is provided with at least two longitudinal grooves of unequal depth.

4. A mould for electroslag remelting of metal ingots as claimed in claim 1, wherein the hollow metallic bars are oval in cross section, the longitudinal groove being provided on at least one of the rounded sides.

5. A mould for electroslag remelting of metal ingots as claimed in claim 4, wherein each hollow metallic bar is provided with at least one additional longitudinal duct for the flow of a coolant.

6. A mould for electroslag remelting of metal ingots as claimed in claim 1 or 5, wherein the cavity or the duct of each hollow metallic bar receives, clear of its wall, a pipe connected to a cooling system.

7. A mould for electroslag remelting of metal ingots as claimed in claim 6, wherein the bottom part of the pipe is provided on the ingot-forming side of the bar with an orifice which communicates the cavity of said pipe with the cavity of the bar or the duct in the bar which accommodates said pipe.

8. A mould for electroslag remelting of metal ingots as claimed in claim 7, wherein said pipe is placed at a distance from the wall of the hollow metallic bar and in contact with the opposite wall of said bar.

9. A mould for electroslag remelting of metal ingots as claimed in claim 6, wherein the gap between the pipe and the wall of the hollow metallic bar accommodates vertical partitions in the plane passing through the longitudinal centre lines of the hollow metallic bar of the arcuated surface of the longitudinal groove.

10. A mould for electroslag remelting of metal ingots as claimed in claim 9, wherein the pipe is offset with respect to the longitudinal centre line of the hollow metallic bar toward the ingot-forming wall thereof.

11. A mould for electroslag remelting of metal ingots as claimed in claim 1, wherein the external side of each hollow metallic bar is provided transversally with at least one groove for receiving said band which encompasses the mould wall.

12. A mould for electroslag remelting of metal ingots as claimed in claim 11, wherein the band carries a header for distributing a coolant.

13. A mould for electroslag remelting of metal ingots as claimed in claim 11, wherein each band is provided with a cavity for the flow of a coolant.

14. A mould for electroslag remelting of metal ingots substantially as herein described with reference to and as illustrated in the accompanying drawings.