Electrode casing assembly and method of assembling an electrode casing

Abstract

The invention relates to an electrode casing, particularly for a Soderberg electrode, and a method for welding the casing. The electrode casing element comprises a tubular shell with a substantially continuous sidewall and a hollow core. A plurality of fins extend from the inner surface of the shell into the hollow core. Additionally, a guide formation is positioned adjacent to at least one fin, with its first end secured to the sidewall and its body extending radially inward into the hollow core. An opening is defined between the guide formation's body and the adjacent fin, facilitating improved assembly and welding of the electrode casing.

Description

[0001] ELECTRODE CASING ASSEMBLY AND METHOD OF ASSEMBLING AN ELECTRODE CASING

[0002] BACKGROUND TO THE INVENTION

[0003] THIS invention relates to an electrode casing, and more particularly but not exclusively to an electrode casing assembly for a Soderberg electrode. The invention also extends to a method of welding the electrode casing.

[0004] Arc furnaces are frequently used in the steel and ferro alloy production industry during metallurgical smelting operations. An electric arc furnace comprises one or more electrodes that extend into a furnace. Lower ends of the electrodes are located adjacent a furnace load, and in use supply the required energy to melt the load by forming an electric arc between the electrode and the furnace load. The electric current required to achieve the “arcing” is conducted to the electrode by way of conductive contact shoes, which provides a conductive path between the energy source and the electrodes.

[0005] Soderberg electrodes are a specific type of electrode used in certain types of arc furnaces called Soderberg furnaces. Soderberg electrodes are made by mixing a paste-like mixture of carbon and other additives, which is then baked and solidified inside an elongate tubular casing into the shape of an electrode. In a Soderberg furnace, the electrodes are inserted vertically into the furnace, and the electrodes are gradually consumed during the melting process. As the lower part of the electrode is consumed, more paste is continuously added from the top of the electrode to maintain a consistent electrode length. This, of course, means that the casing also has to be extended continuously, in order to form a cavity for receiving the paste.

[0006] The advantage of Soderberg electrodes is that they allow for continuous operation of the furnace without the need to stop and replace the electrodes frequently. This makes them well-suited for long-duration operations and large-scale industrial applications. However, the electrode requires continuous extension (i.e. adding additional cylindrical sections) as mentioned above. In practice, this typically entails positioning and welding a new cylindrical extension casing onto an operatively upper end of the electrode.

[0007] In one known approach, the process of adding new extension casings to Soderberg electrodes requires manual intervention (alignment, preparation and welding) to ensure proper alignment and attachment. Skilled operators and artisans are responsible for performing these tasks accurately and securely, which skills are often not readily available. Welding of the casings furthermore takes place in harsh conditions and in a dangerous environment on top of an active arc furnace, resulting in potential exposure to heat, fumes, smoke and live electrical components. All of the above also combine to make the process time-consuming and dangerous.

[0008] In other cases, robotic or automated welding can be utilized for attaching additional casing sections to Soderberg electrodes. While manual attachment is the more common method, automation offers advantages in terms of safety, precision, consistency, and efficiency. Robotic arms equipped with welding tools can handle the electrode sections and perform the welding operation based on predefined instructions. This can help streamline the process, reduce human error, and enhance productivity. While the implementation of robotic or automated welding for Soderberg electrode casing attachment may not be as widespread as manual methods, it is an area where advancements in automation and robotics can potentially offer benefits in terms of efficiency and quality control.

[0009] One example of a proposed semi-automated system is disclosed in WO 2020 / 222653 (“Johansson”). This invention relates to a device for welding an end of a casing extension to an electrode casing. The device comprises a clamping ring configured to surround and attach to a section of the electrode casing. A robot is located on the clamping ring and is displaceable relative to the clamping ring in order for the robot to be able to travel around the circumference of the electrode. A welding gun is provided at the one end of the robot. The invention further relates to a method for welding cylindrical sections of a casing by using such a device, the method comprising the steps of a) positioning and clamping the clamping ring at the correct position, b) moving the robot along the clamping ring to the correct position for welding, c) welding the sections to each other by the welding gun of the robot, and d) releasing the clamping ring.

[0010] Internal robotic welding of structures such as vessels, pipes and tanks is also well known in the art, and welding does not have to be done from the outside, as is disclosed in Johansson. It is equally obvious to weld electrode casings from the inside, for example using a standard articulated robotic arm is known in the art, for example an ABB Rotek IRB 760 or an ABB IRB 1520ID robotic welder. A number of robotic arms can also be secured to one another in order to obtain more degrees of freedom.

[0011] Although a person skilled in the art could easily select a robotic welder arrangement that will be suitable for welding an electrode casing for a Soderberg electrode from the inside, the casing itself still needs to be properly aligned - and should be easy to align - to ensure that the process can be fully automated with the required level of confidence and quality. Existing electrode casings are not designed with this in mind. It has been proposed to provide guide formations to assist with the alignment of two casing sections, for example in WO2022 / 038426, but in the proposed design the guiding formation forms a blind pocket which means that even small variations in the shape and configuration of the casings will result in the two sections not accurately engaging (because the fins have to bottom out in the blind ends of the guiding formations). In addition, with this configuration the weld area is also reduced, as one will not be able to weld the bottom end of the fin (which will be housed inside the guide formation).

[0012] It is accordingly an object of the invention to provide an electrode casing assembly for a Soderberg electrode that will, at least partially, alleviate the above shortcomings.

[0013] It is also an object of the invention to provide an electrode casing assembly for a Soderberg electrode which will be a useful alternative to existing casings.

[0014] It is a further object of the invention to provide a method of welding an electrode casing that will be an improvement over existing methods.

[0015] SUMMARY OF THE INVENTION

[0016] According to the invention there is provided an electrode casing element, suitable for use with a Soderberg electrode, the casing element including: a tubular shell having a substantially continuous sidewall and a hollow core; a plurality of fins extending from an inner surface of the tubular shell into the hollow core; a guide formation located adjacent at least one of the fins; wherein the guide formation has a first end that is secured to the sidewall of the shell, and a body extending radially inwardly from the sidewall into the hollow core, with an opening being defined between a body of the guide formation and the fin.

[0017] There is provided for a plurality of guide formations to be provided, with each guide formation located adjacent a separate fin.

[0018] The guide formation may terminate in a second end, and the second end may be located in the proximity of an inner end of the fin.

[0019] There is provided for a guide formation and an adjacent fin not to be secured to one another.

[0020] There is provided for the guide formation to include an operatively upper zone which is angularly offset relative to the base of the guide formation, in order for the upper zone in use to form a tapering receiving mouth in combination with the fin.

[0021] There is provided for the guide formation to be located towards an operatively upper end of the shell, with the fins extending all the way down to and beyond an operative lower end of the shell.

[0022] More particularly, there is provided for the fins to protrude beyond the lower end of the shell.

[0023] According to a further aspect of the invention there is provided a casing assembly including two casing elements, wherein a protruding end of a fin of an operatively upper casing element is configured in use to be received by the guide formation of the operatively lower casing element.

[0024] According to a further aspect of the invention there is provided a method of welding a casing assembly, the method including the steps of - providing a first, operatively lower, casing element as described above;

[0025] - lowering a second, operatively upper, casing element onto the first casing element; and

[0026] - allowing a protruding fin of the second casing element to protrude through a gap formed between a guiding formation of the first casing element and a fin of the first casing element.

[0027] BRIEF DESCRIPTION OF THE DRAWINGS

[0028] A preferred embodiment of the invention is described by way of a nonlimiting example, and with reference to the accompanying drawings in which:

[0029] Figure 1 is a perspective view of two casing elements of the casing assembly in accordance with the invention, with an operatively upper casing element spaced apart from the operatively lower casing element;

[0030] Figure 2 shows the assembly of Figure 1 , with the two casing elements in an engaged configuration;

[0031] Figure 3 is a cross-sectional perspective view of the interface between the two casing elements of Figure 1 ;

[0032] Figure 4 is a cross-sectional perspective view of the interface between the two casing elements of Figure 2;

[0033] Figure 5 is an enlarged view of a guide formation and fin interface of Figure 1 ; Figure 6 is an enlarged view of a guide formation and fin interface of Figure 2;

[0034] Figure 7 is a cross-sectional side view of the guide formation and fin interface of Figure 1 ; and

[0035] Figure 8 is a cross-sectional side view of the guide formation and fin interface of Figure 2.

[0036] DETAILED DESCRIPTION OF INVENTION

[0037] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted," "connected," "supported," and "secured" and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings and are thus intended to include direct connections between two members without any other members interposed therebetween and indirect connections between members in which one or more other members are interposed therebetween. It is noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the," and any singular use of any word, include plural referents unless expressly and unequivocally limited to one referent. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.

[0038] Referring to the drawings, in which like numerals indicate like features, a non-limiting and simplified example of a casing assembly in accordance with the invention is indicated by reference numeral 10.

[0039] The casing assembly 10 comprises a plurality of casing elements 20 which are configured to be stacked on top of one another to define one elongate casing assembly 10. Each casing element 20 has an upper section that is configured and dimensioned to engage a lower section of another casing element, as is described in more detail below.

[0040] A casing element 20 comprises a cylindrical shell 21 having an operatively upper end 21.1 and an operatively lower end 21.2. The shell 20 has a continuous sidewall 22, with a void or hollow core 23 formed inside the shell 21 , for in use receiving the electrode paste (not shown).

[0041] A plurality of elongate fins 24 extend radially inwardly from an inner surface of the shell 21 , and more particularly from the sidewall 22 of the shell 21. These fins 24 provide structural rigidity to the shell 21 , and hence the casing assembly 10, and at the same time also provides engagement surfaces to which the paste can adhere when solidifying.

[0042] The fins 24 are made from elongate strips of metal. Each fin has an operatively upper end 24.1 that protrudes beyond the upper end 21 .1 of the shell 21 , and an operatively lower end 24.2 that protrudes beyond a lower end 21 .2 of the shell 21 . A body section 24.3 extends between the two ends, and terminates in an inner edge 24.4, which is the end of the fin facing the void or hollow core 23 of the shell 21 . Paste-receiving apertures 60 are provided along the length of the fins 24. Securing apertures 50 are also provided towards the upper 24.1 and lower 24.2 ends of the fins. In the embodiment shown in the figures, each fin 24 also includes a guide formation 25. The guide formation 25 is in the form of a cantilevered extension that extends inwardly from the inner surface of the sidewall 22. Each guide formation 25 extends parallel to an adjacent fin 24, but without being secured to the fin 24. More particularly, a gap 26 is formed between the guide formation 25 and the adjacent fin 24. Each guide formation 25 has a first end 25.1 that is secured to the sidewall 22 of the shell 21 , a second end 25.3 that terminates in the in the proximity of the inner edge 24.4 of a fin, and a body 25.2 extending between the first end 25.1 and the second end 25.3. The body 25.2 is parallel to, but spaced apart from, the body 24.3 of an adjacent fin 24.

[0043] An offset section 25.4 is provided at the upper end of the body 25.2 of each guide formation 25. More particularly, the offset section is angularly offset relative to the body 25.2 of the guide formation 25, and therefore also relative to the fin 24. The configuration is such that the distance between the offset section 25.4 and the fin 24 increases from the operatively lower to the operatively upper direction, with the guiding formation 25 thus forming a wedge-shaped receiving mouth. The receiving mouth guides a protruding lower end 24.2 of an operatively upper casing element 30 into the gap 26 defined by the guide formation located towards the protruding upper end 24.1 of an operatively lower element 40.

[0044] As can be seen in Figures 4 and 6, the lower end 24.2 of the fin 24 of the upper casing element 30 protrudes through the gap 26 formed between the guide formation 25 and the fin 24 of the lower element 40, and does not bottom out in a blind slot formed by the guiding formation, as is the case in prior art configurations.

[0045] In addition to depicting a position of the two elements prior to engagement, Figures 3 and 5 also show an alternative configuration of the casing assembly where the fins are secured to one another through a gap between the two shells (typically using the securing apertures 50) and then welded from the outside. In this configuration the guide formation is not utilized, but this mode of securement is part of the prior art and therefore not included in the scope of the invention.

[0046] The important improvement aspect of this invention is that the guide formations is configured to guide the fin of the upper casing element relative to the fin of the operatively lower casing element, but at the same time still allowing the lower end of the upper fin to pass through a gap formed between the lower fin and the guide formation due to the specific configuration of the guide formation. This means that the upper fin will in use protrude beyond the guide formation, thus providing two additional surfaces that can be welded (i.e. the bottom end of the upper fin can be welded to the side of the lower fin, and the part of the bottom fin protruding beyond the guide formation can also be welded to the bottom edge of the guide formation). The fact that the upper fin can slide through the gap also means that the two sections are easier to match up, as the end of the upper fin does not bottom out in a closed guiding aperture. Small inaccuracies in the fabrication of the casing elements, and in particular the fins, will therefore not result in misalignment or difficulty in aligning the two casing elements.

[0047] It will be appreciated that the above is only one embodiment of the invention and that there may be many variations without departing from the spirit and / or the scope of the invention. It is easily understood from the present application that the particular features of the present invention, as generally described and illustrated in the figures, can be arranged and designed according to a wide variety of different configurations. In this way, the description of the present invention and the related figures are not provided to limit the scope of the invention but simply represent selected embodiments.

[0048] The skilled person will understand that the technical characteristics of a given embodiment can in fact be combined with characteristics of another embodiment, unless otherwise expressed or it is evident that these characteristics are incompatible. Also, the technical characteristics described in a given embodiment can be isolated from the other characteristics of this embodiment unless otherwise expressed.

Claims

CLAIMS1. An electrode casing element, suitable for use with a Soderberg electrode, the casing element including: a tubular shell having a substantially continuous sidewall and a hollow core; a plurality of fins extending from an inner surface of the tubular shell into the hollow core; a guide formation located adjacent at least one of the fins; wherein the guide formation has a first end that is secured to the sidewall of the shell, and a body extending radially inwardly from the sidewall into the hollow core, with an opening being defined between a body of the guide formation and the fin.

2. The electrode casing element of claim 1 wherein the guide formation terminates in a second end, with the second end located in the proximity of an inner end of the fin.

3. The electrode casing element of claim 1 or claim 2 wherein the guide formation and the adjacent fin are not secured to one another.

4. The electrode casing element of any one of the preceding claims wherein the guide formation includes an operatively upper zone which is angularly offset relative to the base of the guide formation, in order for the upper zone in use to form a tapering receiving mouth in combination with the fin.

5. The electrode casing element of any one of the preceding claims wherein the guide formation is located towards an operatively upper end of the shell, with the fins extending all the way down to and beyond an operative lower end of the shell.

6. The electrode casing element of claim 5 wherein the fins protrude beyond the lower end of the shell.

7. The electrode casing element of any one of the preceding claims including a plurality of guide formations, wherein each guide formation is located adjacent a separate fin.

8. A casing assembly including two casing elements as claimed in ant one of claims 1 to 7, wherein a protruding end of a fin of an operatively upper casing element is configured in use to be received by a guide formation of an operatively lower casing element.

9. A method of welding a casing assembly, the method including the steps of:- providing a first, operatively lower, casing element as claimed in any one of claims 1 to 7;- lowering a second, operatively upper, casing element as claimed in any one of claim a to 7 onto the first casing element; and- allowing a protruding fin of the second casing element to protrude through a gap formed between a guiding formation of the first casing element and a fin of the first casing element.

10. The method of claim 9 including the step of welding a bottom end of a protruding fin of the second casting element to the fin of the first casing element.

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