NL2020368B1 - A component for an electric furnace - Google Patents

Abstract

A component (10) for an electric furnace forms part of a lower electrode assembly (100). The component comprises a body (26) which is made by an additive manufacturing method (28) utilising at least a first material (30). In an example embodiment, the component is a pressure ring segment. The component may also be in the form of a contact shoe (12), a biasing device (14), a hanging device (16, 18), a sealing device (20, 21), an insulating device (22) and a heat shield (24) forming part of the lower electrode assembly.

Description

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Θ 2020368

(2?) Application number: 2020368

Application submitted: 1 February 2018 © Int. CL:

B22F 1/00 (2018.01) B22F 3/105 (2018.01)

0 Application registered: 0 Patent holder (s): August 12, 2019 METIX (PTY) LIMITED in RIVONIA, South Africa, ZA. 0 Request published: 0 Inventor (s): 0 Patent granted: Brett Nicholas Belford August 12, 2019 in JOHANNESBURG (ZA). Peter William Douglas in Centurion (ZA). 0 Patent issued: August 13, 2019 © Authorized representative: ir. J.C. Volmer et al. In Rijswijk.

A COMPONENT FOR AN ELECTRIC FURNACE

57) A component (10) for an electric furnace forms part of a lower electrode assembly (100). The component comprises a body (26) which is made by an additive manufacturing method (28) utilizing at least a first material (30). In an example embodiment, the component is a pressure ring segment. The component may also be in the form of a contact shoe (12), a biasing device (14), a hanging device (16, 18), a sealing device (20, 21), an insulating device (22) and a heat shield (24) forming part of the lower electrode assembly.

NL B1 2020368

This patent has been granted regardless of the attached result of the research into the state of the art and written opinion. The patent corresponds to the documents originally submitted.

P33486N L00 / ME

Title: A COMPONENT FOR AN ELECTRIC FURNACE

INTRODUCTION AND BACKGROUND

This invention relates to a component for an electric furnace and more particularly to a lower electrode component such as, but not limited to, a pressure ring segment, a contact plate, and other components forming part of the general lower electrode assembly including heat shields, bellows, hangers, brackets, seals and insulating devices. The invention further relates to a method of manufacturing the component.

Electric furnaces typically include a cylindrical electrode with lower electrode components such as pressure ring segments and contact plates or contact shoes arranged around the electrode. These components are generally made by conventional manufacturing techniques or methods by casting or forging a copper body from copper or a copper-based alloy and providing cooling passages within the body for circulating a cooling fluid, such as water. These internal cooling passages may be formed by drilling holes into the body, as is the case with a forged body, or by providing pre-formed pipes and casting the copper body around these pipes, as is the case with the cast body. When adopting the forged and drilled conventional manufacturing technique, the copper body is heated after drilling and are into a curved shape to form the component, whereafter some of the holes are plugged, for example by welding, press-fitting or other means. The possible shapes and configurations of the cooling passages are limited when using the aforementioned forged manufacturing methods. When using the casting technique, greater flexibility in the body and cooling channel geometry is possible. But the casting technique produces a work piece with compromised mechanical properties due to the larger grain structures that are naturally formed during the process. Furthermore, fusion of the preformed pipes with the molten metal being cast is problematic. Defects on the metal-pipe boundary are common and lead to heat transfer retardation.

The above forging and casting methods require multiple production stages including casting, forging, cooling pipe cutting, forming and welding, rough cutting, drilling, heating, bending, machining and welding. Hence, such an intensive multi-stage process requires many different machines and human skill sets to produce a final product. Each stage of manufacture introduces risk or non-conformity. The conventional manufacturing techniques typically take weeks to produce a single component.

-2In use, the components are subject to high temperatures in the furnace over years of operation. The necessity to cool these components in an electric furnace environment has necessitated the use of materials with superior thermal conductivities and relatively good mechanical properties, for which copper has become the preferred material of construction. With the use of copper to form the body of the component, even elevated temperatures that pose no risk to the component per se, do accelerate the phenomenon of creep. Create deforms the copper body at elevated temperatures despite relatively low stresses, continuously reducing the geometric accuracy of the component and impeding the component's ability to perform its inherent function. To mitigate the impact of creep, two remedies are generally used. Firstly, by selecting specialized and often expensive copper alloys to increase softening temperature, to improve hardness and to extend creep life. Secondly, by increasing the cross-sectional area of the component, so that stress in the component, which is a function of area, is reduced. The latter option results in large and numerical components which are "oversized" to add creep resistance rather than provide any significant thermal advantages.

Hence, the known components and methods may not be suitable for at least some applications.

OBJECT OF THE INVENTION

Aw, it is an object of the present invention to provide a component for an electric furnace and a method of manufacturing the component, with which at least some of the above problems may be alleviated or which may provide a useful alternative to the known components and / or methods.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a component for an electric furnace, the component including a body which is made by an additive manufacturing method utilizing at least a first material.

The component may be any one, but not limited to, a pressure ring segment, a contact plate or a contact shoe, a bellows or biasing device, a pendant or hanging device, an insulating device and a heat shield.

The component may form a part of a lower electrode assembly for an electric furnace. The lower electrode assembly normally comprises the pressure ring segment, the contact plate,

-3the biasing device, the hanging device, the heat shield, the insulating device and a sealing device such as a pressure ring tip seal.

The additive manufacturing method may include a "3D printing" technique including, but not limited to any one of: laser sintering, laser metal deposition or other associated methods and / or techniques, including, for example, the method known in the trade as “ electron beam additive manufacturing (EBAM®).

The body of the component may comprise a frame or skeleton for supporting a remainder of the body.

The component, including the frame and the remainder of the body, may be made by forming sequential layers of the body during a single run of the additive manufacturing method.

The remainder of the body may be made of the first material and the frame may be made of a second material.

The first and second materials may be metallic or a metal alloy.

The first and second materials may be different from one another.

The first material may be selectable from a group including copper and copper-based alloys including but not limited to alloys containing silver, nickel, chrome, zirconium, iron, silicon and tin.

The second material may be selectable from a group including: carbon steel, ferritic and / or austenitic stainless steel and ferrous alloys including ferroalloys, etc.

The first and second materials may be fused to another during the additive manufacturing method, for example by close proximity melting and re-solidification.

The body of the component may at least be partially cladded by a cladding layer or a third material. The third material may be selectable from a group including ceramic material, metal alloys, silicates or silicon alloys etc. The cladding layer may be a heat insulating or heat dispersing layer.

-4 The cladding layer may be formed during the single run or the additive manufacturing method.

The body may define an internal cooling passage for a cooling fluid.

The cooling passage may be provided by forming a void in the body or the component. The void may be formed during the single run or the additive manufacturing method.

It will be appreciated that utilizing the additive manufacturing method, the dependence on conventional void formation is absent and the cooling passage may be created by forming a void or irregular shape.

The cooling passage may have a varying cross section along its length.

A variety of cooling circuits may be formed which run separately and / or which combine with one another.

The cooling passage or the multiple of cooling circuits may have a predetermined internal geometry (e.g. spirals) which creates controlled turbulence or the cooling fluid for the benefit of heat transfer, etc.

According to a second aspect of the invention there is provided a method of manufacturing a component for an electric furnace, the method including utilizing an additive manufacturing technique to form the component layer by layer, utilizing at least a first material.

LETTER DESCRIPTION OF THE ACCOMPANYING DIAGRAMS

The invention will now be further described, by way of example only, with reference to the accompanying diagrams:

figure 1 is a diagrammatic perspective view of a lower electrode assembly or components for an electric furnace;

figure 2 is a diagrammatic perspective view of a pressure ring segment for the electric furnace;

figure 3 is a diagrammatic representation of an additive manufacturing method showing the pressure ring segment in a partially completed form; and figure 4 is a diagrammatic perspective view of the pressure ring segment, illustrating a frame and internal cooling channels.

-5DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

An example embodiment of a component for an electric furnace forming part of a lower electrode assembly 100 (shown in figure 1) is generally designated by the reference numeral 10 in the figures.

In the example embodiment, the component 10 is a pressure ring segment. The component may also be in the form of a contact shoe or contact plate 12, a biasing device or bellows 14, a hanging device 16, 18, a sealing device 20, 21, (such as a pressure ring tip seal 20 and a rope seal 21), a heat shield 24 or insulating device 22 forming part of the lower electrode assembly 100.

Referring to figures 2 and 3, the component 10 comprises a body 26 which is made by an additive manufacturing method 28 utilizing at least a first material 30. Figure 3 shows the component 10 in a partially completed form, during the additive manufacturing method 28 and in figure 2 the component 10 is shown after the additive manufacturing method 28 is completed.

The additive manufacturing method 28 is preferably a "3D printing" technique including, but not limited to any one of: laser sintering, laser metal deposition or other associated methods and / or techniques including, for example, the method known in the trade as “ electron beam additive manufacturing (EBAM®). For explanatory purposes the term "3D printing" will be used as a synonym for any one of the aforementioned methods. A 3D printing apparatus 32 is provided for performing the additive manufacturing method 28.

Referring to figures 3 and 4, the body 26 of the component 10 comprises a skeleton or frame 34 for supporting a remainder 30 of the body 26. The remainder 30 of the body is made of the first material and the frame 34 is preferably made of a second material. The body 26 or the component 10 is at least partially cladded by a cladding layer 36 or a third material. The third material is preferably in the form of a heat insulating or heat dispersing material so that the cladding layer 36 provides resistance to heat transfer from an interior of the furnace to the component 10. The body 26 further defines an internal cooling passage 38 for a cooling fluid. Other insulating or sealing devices forming part of the lower electrode assembly 100 (shown in figure 1) may also be used utilizing the additive manufacturing method.

Referring to figure 3, the component 10, including the frame 34 and the remainder 30 or the body 26, is preferably made by forming sequential layers of the body. 3D printing apparatus 32 initiates the method 28 by depositing a first layer of the body 26. Sequential layers are

-6then deposited by 3D printing apparatus in a layer by layer fashion, until the component 10 is completed. The sequential process of depositing layers from a first layer to a last layer of the body 26 may be referred to as a single run of the additive manufacturing method 28. During the single run, the frame 34, the remainder 30 of the body 26, the cladding layer 36 and the cooling passage 38 are formed. The 3D printing apparatus is configured to deposit the first material 30, the second material 34 and the third material 36. As indicated by the three arrows in Figure 3, the first, second and third materials 30, 34 and 36 are welded, sintered or fused together, depending on the particular additive manufacturing method or technique utilized. The first, second and / or third materials may also be fused to one or another bound on a molecular or microscopic level during additive manufacturing. The cooling passage 38 is provided by forming a void in the body 26 or the component during the single run of the additive manufacturing method 28.

Referring to figure 4, the remainder 30 or the body 26 is shown in broken lines. The frame 34 preferably comprises a variety of structural elements for supporting the remainder 30 of the body 26. The structural elements comprise pillars 34.1 and supporting members or ribs 34.2. An inlet 40 and an outlet 42 of the cooling passage 38, a variety of fastening locations 44 and a sealing channel 46 are preferably also made of the second material 34 during the single run of the additive manufacturing method 28. Sealing devices 20, 21 and insulating device 22 (shown in figure 1) are preferably made separately and may also be made by a 3D printing technique.

The first and second materials 30, 34 are preferably metallic or a metal alloy. The first material 30 is selectable from a group including copper and copper-based alloys including but not limited to alloys containing silver, nickel, chrome, zirconium, iron, silicon and tin. The second material 34 is selectable from a group including: carbon steel, ferritic and austenitic stainless steel, etc. The third material 36 or the cladding layer is preferably a heat insulating or heat dispersive material and is selectable from a group including ceramic material, metal alloys, silicates or silicon alloys, etc.

It will be appreciated that there are many variations in detail on the invention as described and / or described without departing from the scope and spirit of this disclosure.

For example, the additive manufacturing of the pressure ring segment 10 is described above, but other components of the lower electrode assembly 100 may also be manufactured utilizing the method 28. It will be further appreciated that different parts of the components may be manufactured separately and assembled together at a later stage, or manufactured

-7during the single run or the additive manufacturing method. The components may also be manufactured utilizing only a single one of the first, second and third materials. Annealing of the body 26 may not be required after the component 10 is manufactured using the additive manufacturing method 28. By utilizing the frame 34, creep of the remainder 30 or the body 26 is prevented or at least alleviated.

It will be further appreciated that by utilizing the method 28, many different shapes and configurations of the cooling passage 38 are possible. No drilling or plugging of the body 26 is required to form the cooling passage 38. As described above, the inlet 40 and outlet 42 of the cooling passage 38 may be formed from the second material 34, preferably stainless steel. Other parts of the cooling passage 38 may also be formed from the second material 34 or even from the third material 36. The cooling passage 38 may be in the form of a series cooling circuit, an example or which is illustrated in figure 4. Parallel cooling circuits or arrangements are also possible, two or more inlets and two or more outlets are provided for the cooling fluid.

It will be appreciated that utilizing the additive manufacturing method, the dependence on conventional void formation is absent and the cooling passage 38 may be created by forming a void or irregular shape. The cooling passage 38 may have a varying cross section along its length. A variety of cooling circuits (not shown) may be formed which run separately and / or which combine. The cooling passage 38 or the multiple of cooling circuits may have a predetermined internal geometry (e.g. spirals) which creates controlled turbulence or the cooling fluid for the benefit of heat transfer, etc.

As described above, the cooling passage 38, frame 34 and cladding layer 36 are provided in the pressure ring segment 10. However, other cooling passages and / or frames and or cladding layers may be similarly provided in the other components of the lower electrode assembly 100, such as in the contact shoe or contact plate 12, in the biasing device or bellows 14, in the hanging device 16, 18, in the sealing device 20, 21, in the insulating device 22 and in the heat shield 24.

It will yet be further appreciated that the invention provides several advantages about the prior art. Firstly, the components may be made using a single setup and may be completed in a single run of the additive manufacturing method. The manufacturing of the component may be completed in more hours while prior art methods require weeks to complete.

-8Secondly, by utilizing additive manufacturing, the first and second materials (which may be dissimilar metals) may be fused to one another and / or embedded in one another. Hence, the component may be given as a desirable property of the first material 30 (such as the ability to cool rapidly and to protect the second material 34) while also imparting a desirable property of the second material 34 (such as strength and creep resistance) to the component 10. This symbiotic relationship on a metallurgical level between the first and second materials results in an improved component compared to prior art components.

Thirdly, in addition to the first and second materials, the third material is preferably melted with and re-solidified to bond or bond to the first and / or second materials to form the cladding layer for thermal insulation, arch or wear resistance. Utilizing the additive manufacturing method, this cladding may be positioned accurately and efficiently on designated surfaces or the component utilizing a microscopically fused bond that essentially extends the first and / or second materials.

Fourthly, cooling or electric furnace equipment operating inside the furnace is paramount. Whilst the use of embedded cooling pipes in cast components or drilling and plugging in forged components has provided sufficient cooling to date, both have distinct lead time, complexity, geometry and inherent reliability drawbacks. With additive manufacturing, any shape, direction, number and / or cross-sectional area or cooling passages or channels may be introduced to specifically target high heat areas of the component without any need for the introduction of a plug, without the limitation of the fact that a drill cannot go around a corner and without the limitation or not being able to vary the drill's cross-sectional area along the length of a drilled port, etc.

Claims (4)

CONCLUSIONS 1/4 figure 1 FIGURE 2 A component for an electric oven, wherein the component comprises a body made by an additive manufacturing method using at least a first material. The component of claim 1, wherein the component is one of a pressure ring segment, a contact plate, a biasing device, a suspension device, an insulation device, a sealing device, and a heat shield. 3/4 A component according to any of claim 1 and claim 2, wherein the body of the component comprises a frame for supporting a remaining part of the body. The component of claim 3, wherein the frame and the remaining part of the body are made by forming successive layers of the body during a single pass of the additive manufacturing method. A component according to any of claim 3 and claim 4, wherein the remaining part of the body is made of the first material and the frame is made of a second material. The component of claim 5, wherein the first material is selectable from a group comprising copper and copper-based alloys. The component of any of claim 5 and claim 6, wherein the second material is selectable from a group comprising: carbon steel, ferrite and austenitic stainless steel, and ferrous alloys include iron alloys. A component according to any of claims 5 to 7, wherein the first and second materials are fused together during the additive manufacturing process. A component according to any one of the preceding claims, wherein the body of the component is at least partially covered by a coating layer of a third material. Component according to claim 9, wherein the third material is selectable from a group comprising ceramic material, metal alloys, silicates and silicon alloys. A component according to any of claim 9 and claim 10, insofar as they are dependent on claim 4, wherein the coating layer is formed during the single pass through the additive manufacturing method. The component of claim 11, wherein the third material is bonded to one of the first and second materials during the single pass of the additive manufacturing process. A component according to any one of the preceding claims, wherein the body defines an internal cooling passage for a cooling liquid. A component according to claim 13, as far as it is dependent on claim 4, wherein the cooling passage is provided by forming a cavity in the body of the component, during the single passage of the additive manufacturing method. A method of manufacturing a component for an electric oven, the method comprising the use of an additive manufacturing technique for forming the component layer by layer using at least a first material. 4/4 FIGURE 4