DESC:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2016

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
TITLE
“ELECTROSLAG REFINING FURNACE STRUCTURE FOR REMELTING OF HIGHER CAPACITY ELECTRODES”
APPLICANT
(a) Name : Mishra Dhatu Nigam Limited
(b) Nationality : Indian
(c) Address : PO Kanchanbagh, Hyderabad, Telangana – 500058, India

The following specification particularly describes the application and the manner in which it is to be performed.

PRIORITY STATEMENT
The present application hereby claims priority from Indian patent application with the application number 202341024929, filed on 31 March 2023, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD OF INVENTION
The Present invention relates to electroslag refining (ESR) furnaces which are used to process metals and alloys. More particularly, it relates to a newly designed ESR furnace structure for remelting of higher capacity electrodes (20T).

BACKGROUND OF INVENTION
Alloys used for the Aerospace, Defence, Atomic Energy, Power Generation, turbines etc. are subject to stringent requirements to ensure absence of melt related defects such as inclusions and segregation.
In electric furnaces or other installations which use consumable electrodes, it is necessary to know the precise position of the individual electrodes. This is of particular importance for installations in which the electrode tips cannot be seen during furnace operation, for example in the case of closed furnaces or furnaces where the batch is covered. In the case of processes for the production of iron-containing alloys, self-baking electrodes are used, while in the production of silicon metal, pre-baked electrodes are used, these being necessary because of the required purity of the product.
Accordingly, the production of the super alloys used in these applications involves multiple re-melting stages, each of which plays a distinct role in ensuring that the final ingot is defect-free.
Electro Slag refining (ESR) furnace is one among them. Because of the complexity of these processes, high-temperature environments, and high initial and operating costs, trial-and-error based approaches for process design are inadequate.
ESR has been known since the 1930s, but it took many years before it became an acknowledged process for mass production of high-quality ingots. The ESR technology is of interest not only for the production of smaller weight ingots of tool steels and superalloys, but also heavy ingots. Based on the anticipated requirement to produce heavy turbine shaft or 155 mm gun barrels, 20T capacity melting and re-melting furnace is designed and developed.
Accordingly, the present invention discloses a novel electroslag refining furnace structure for remelting of 20T electrodes.

OBJECT OF THE INVENTION
The primary object of the present invention is to provide an improved Electro-Slag Remelting (ESR) furnace structure capable of efficiently re-melting higher capacity electrodes, preferably 20-ton electrodes. The invention aims to overcome the limitations of existing ESR furnace designs by offering enhanced stability, efficiency, and control over the remelting process.
Another objective of the invention is to provide a self-supporting ESR furnace structure that eliminates the need for shed column support, thereby reducing complexity and cost of installation.

SUMMARY OF THE INVENTION
This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the disclosure. This summary is neither intended to identify key or essential inventive concepts of the disclosure nor is it intended for determining the scope of the disclosure.
To overcome the problems mentioned above, the present invention discloses a self-supporting Electro-Slag Remelting (ESR) furnace structure for re-melting 20T electrodes comprising a pivoting column (12) supporting and enabling controlled movement of an electrode into and out of the furnace chamber; a driving column (14) responsible for driving or controlling the movement of a critical component within the furnace; a movable carriage (18) responsible for supporting and moving the electrode assembly within the furnace chamber; a stringer head (20) at the upper portion of the electrode assembly, facilitating connection to a power supply and formation of a molten slag layer during remelting; a mushroom contact electrode tip (22) contributing towards improved contact, stability, and electrode longevity during the remelting process; bus tubes (16, 28) for carrying electrical current from the power source to the electrode, comprising a top bus tube (16) and a bottom bus tube (28); a sliding contact (30) facilitating the transmission of electrical current from the power supply to the electrode within the furnace; bus bars (32) facilitating the transfer of electrical current from the power supply to the electrode assembly; and an automatic melt control system with logic controls, closed-loop control of process parameters, and data acquisition and management system.

BRIEF DESCRIPTION OF THE DRAWINGS
These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Fig. 1 illustrates a novel electro slag refining furnace structure in accordance with an embodiment of the present invention.
Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have necessarily been drawn to scale. For example, the flow charts illustrate the method in terms of the most prominent steps involved to help to improve understanding of aspects of the present disclosure. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiment of the present disclosure so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

DETAILED DESCRIPTION OF THE INVENTION
For the purpose of promoting an understanding of the principles of the present disclosure, reference will now be made to the various embodiments and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the present disclosure is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the present disclosure as illustrated therein being contemplated as would normally occur to one skilled in the art to which the present disclosure relates.
It will be understood by those skilled in the art that the foregoing general description and the following detailed description are explanatory of the present disclosure and are not intended to be restrictive thereof.
Whether or not a certain feature or element was limited to being used only once, it may still be referred to as “one or more features” or “one or more elements” or “at least one feature” or “at least one element.” Furthermore, the use of the terms “one or more” or “at least one” feature or element do not preclude there being none of that feature or element, unless otherwise specified by limiting language including, but not limited to, “there needs to be one or more…” or “one or more elements is required.”
Reference is made herein to some “embodiments”. It should be understood that an embodiment is an example of a possible implementation of any features and/or elements of the present disclosure. Some embodiments have been described for the purpose of explaining one or more of the potential ways in which the specific features and/or elements of the proposed disclosure fulfil the requirements of uniqueness, utility, and non-obviousness.
Use of the phrases and/or terms including, but not limited to, “a first embodiment,” “a further embodiment,” “an alternative embodiment,” “one embodiment,” “an embodiment,” “multiple embodiments,” “some embodiments,” “other embodiments,” “further embodiment”, “furthermore embodiment”, “additional embodiment” or other variants thereof do not necessarily refer to the same embodiments. Unless otherwise specified, one or more particular features and/or elements described in connection with one or more embodiments may be found in one embodiment, or may be found in more than one embodiment, or may be found in all embodiments, or may be found in no embodiments. Although one or more features and/or elements may be described herein in the context of only a single embodiment, or in the context of more than one embodiment, or in the context of all embodiments, the features and/or elements may instead be provided separately or in any appropriate combination or not at all. Conversely, any features and/or elements described in the context of separate embodiments may alternatively be realized as existing together in the context of a single embodiment.
Any particular and all details set forth herein are used in the context of some embodiments and therefore should not necessarily be taken as limiting factors to the proposed disclosure.
The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by “comprises... a” does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.

Functionality of different parts/subassemblies used in the Electro-Slag Remelting (ESR) furnace structure for re-melting 20T electrodes are as follows:
• Traverse (10) – It enables the movement of the electrode within the molten metal bath during the refining or melting process.
• Pivoting Column (12) - it supports and enables controlled movement of an electrode into and out of the furnace chamber.
• Driving Column (14) - responsible for driving or controlling the movement of a critical component within the furnace
• Movable Carriage (18) - responsible for supporting and moving the electrode assembly within the furnace chamber.
• Stringer Head (20) – It is essentially the upper portion of the electrode assembly, where the electrode is connected to the power supply and where the molten slag layer forms during the remelting process. This area is critical for initiating and sustaining the remelting operation.
• Mushroom Contact (22) - refers to a specific type of electrode tip and it contributes towards improved contact, stability, and electrode longevity during the remelting process.
• Ingot (24) – it refers to the solid block of metal typically obtained through casting or solidification of molten metal in a mold.
• Crucible (26) – it refers to container used for holding and heating materials to high temperatures, typically to melt or fuse.
• Bus Tubes Top (16) and Bottom (28)- they are conductive bars or tubes that carry electrical current from the power source to the electrode.
• Sliding Contact (30) – it facilitates the transmission of electrical current from the power supply to the electrode within the furnace.
• Bus Bars (32) - it facilitates the transfer of electrical current from the power supply to the electrode assembly
In view of the problems disclosed above, there exists a need for designing a novel Electro-Slag Remelting (ESR) furnace for re-melting higher capacity electrodes preferably 20-ton electrode.
In an embodiment of the present disclosure, an Electro-Slag Remelting (ESR) furnace of 20T capacity is disclosed. The ESR furnace structure comprises of sub-assemblies – Traverse (10), Pivoting column(12), Driving column (14), Drive column with a moving carriage (18) at the centre to hold the electrode.
In accordance with an embodiment of the present invention, larger ingot of sizes (1,000mm and 1,250mm) of 20 Ton ESR help in better forging reduction ratio for manufacturing big barrels without the process of upsetting during forging. This helps in better grain control of the microstructure for enhanced performance.
The present invention discloses a self-supporting structure obviating the necessity of shed column support. Accordingly, the furnace was designed with a pivoting column (12) and a drive column (14) with a moving carriage (18) at the centre which holds the electrode. The electrode is driven through a ball screw and top mounted electrode drive motor-gearbox unit. The furnace has two melting stations and either station can be selected by moving the moving carriage (18) driven by a drive unit (14) mounted under the moving column over a rail fixed on the ground. There are copper crucibles of approx. 1000mm and 1250mm diameter located inside water jackets.
In accordance with an embodiment of the present invention, the newly designed self-supporting structure of furnace consist of Electrode drive arrangement, wherein Electrode drive is through a motorised gearbox unit. The electrode which is hung from the movable carriage is driven up and own through a ball screw and the above gearbox unit. The gearbox unit has two separate motorised gearboxes connected through a phase shifter gearbox. The small, motorised gearbox which has an AC servomotor is used for low speed electrode feed movements and the big motorised gearbox has an AC motor used for rapid movements. The phase shifter gearbox provides the option for driving the ball screw through either of these motors without disconnecting the other. The following was the drive sizing calculations for maximum melting time feed rate of 200mm/min and maximum rapid movement rate of 1500mm/min.
In accordance with an embodiment of the present invention, the furnace is designed with static mould thus obviating the problems associated with multiple electrode changes.
Further, the AC current carrying bus tubes are positioned in fully co-axial manner so as to reduce the size of power supply and improve overall efficiency. This also decreases the undesirable magnetic stirring of the melt and eliminates the stray field eddy current heating of the surrounding steel works.
In accordance with an embodiment of the present invention, the mechanical structure of the furnace was designed with driving (14) and pivoting columns (12) (in contrast to overhung design) with centrally hung electrode to improve the overall stability in operation of the furnace.
In accordance with an embodiment of the present invention, the electrode drive is an efficient and compact configuration of two AC motors (one servo) with attached helical gearboxes connected to a differential gearbox (phase shifter gearbox with planetary and worm gear modules) through a bevel gear arrangement. The position and feed rate of the electrode is read and controlled through encoder and resolver. This arrangement provides accurate feed control during melting.
In accordance with an embodiment of the present invention, the furnace is provided with Automatic Melt control System with logic controls, closed loop control of process parameters and data acquisition and management system.

ADVANTAGES AND APPLICATION
The present invention offers an advantage of making larger ingot of sizes 1,000mm and 1,250mm of 20 Ton. Further, the present invention helps in better forging reduction ratio for manufacturing big barrel without the process of upsetting during forging. This helps in better grain control of the microstructure for enhanced performance.
,CLAIMS:CLAIMS
We claim:
1. A self-supporting Electro-Slag Remelting (ESR) furnace structure for re-melting 20T electrodes comprising:
a. A pivoting column (12) supporting and enabling controlled movement of an electrode into and out of the furnace chamber;
b. A driving column (14) responsible for driving or controlling the movement of a critical component within the furnace;
c. A movable carriage (18) responsible for supporting and moving the electrode assembly within the furnace chamber;
d. A stringer head (20) at the upper portion of the electrode assembly, facilitating connection to a power supply and formation of a molten slag layer during remelting;
e. A mushroom contact electrode tip (22) contributing towards improved contact, stability, and electrode longevity during the remelting process;
f. Bus tubes (16, 28) for carrying electrical current from the power source to the electrode, comprising a top bus tube (16) and a bottom bus tube (28);
g. A sliding contact (30) facilitating the transmission of electrical current from the power supply to the electrode within the furnace;
h. Bus bars (32) facilitating the transfer of electrical current from the power supply to the electrode assembly; and
i. an automatic melt control system with logic controls, closed-loop control of process parameters, and data acquisition and management system.

2. The Electro-Slag Remelting (ESR) furnace structure as claimed in claim 1, further comprising a traverse (10) enabling movement of the electrode within the molten metal bath during the refining or melting process.
3. The Electro-Slag Remelting (ESR) furnace structure as claimed in claim 1, wherein the electrode drive comprises a motorized gearbox unit driving the electrode via a ball screw.
4. The Electro-Slag Remelting (ESR) furnace structure as claimed in claim 1, wherein the furnace is designed with static molds to obviate problems associated with multiple electrode changes.
5. The Electro-Slag Remelting (ESR) furnace structure as claimed in claim 1, wherein the mechanical structure comprises driving and pivoting columns with a centrally hung electrode for improved stability during furnace operation.
6. The Electro-Slag Remelting (ESR) furnace structure as claimed in claim 1, wherein the electrode drive comprises two AC motors with attached helical gearboxes connected to a differential gearbox via a bevel gear arrangement, providing accurate feed control during melting.
7. The Electro-Slag Remelting (ESR) furnace structure as claimed in claim 1, wherein the AC current carrying bus tubes are positioned in a fully co-axial manner to reduce the size of the power supply and improve overall efficiency, thereby decreasing undesirable magnetic stirring of the melt and eliminating stray field eddy current heating of the surrounding steelworks.