Arc striking device and arc striking method for electroslag smelting casting end cover seat ring

Abstract

The invention relates to the technical field of electroslag casting smelting, in particular to an arc striking device and an arc striking method for an electroslag casting end cover seat ring. Comprising an arc-striking crystallization mechanism which is provided with an arc-striking slagging unit and a supporting unit, and a first containing cavity with an upward opening is defined by the arc-striking crystallization mechanism; an arc striking slagging section and a variable cross-section transition section are arranged on the top surface of the arc striking slagging unit; the inner diameter of the variable cross-section transition section is in an expansion trend along the flowing direction of the slag bath; the end cover seat ring main body crystallization mechanism is provided with a second accommodating cavity with a downward opening; an arc striking electrode is arranged in the second accommodating cavity, a first electrode of the arc striking electrode is matched with the arc striking slagging section, and a second electrode of the arc striking electrode is matched with the variable cross-section transition section; a water-cooling heat dissipation unit is arranged between the arc striking slagging unit and the supporting unit, the arc striking slagging unit is made of a first material, the supporting unit is made of a second material, and the thermal conductivity of the first material is higher than that of the second material. In this way, the problems existing in the electroslag casting process of an existing end cover seat ring are solved.

Description

Technical Field

[0001] This invention relates to the field of electroslag casting technology, and more specifically, to an arc-initiating device and method for electroslag casting end cap seat rings. Background Technology

[0002] As a core component of the system's energy conversion, the operational stability of the half-speed steam turbine generator directly affects the system's safe and efficient operation. The end cover seat ring, as a supporting component of the core rotor of the half-speed steam turbine generator, endures high loads, alternating stresses, and complex operating conditions during long-term unit operation. Therefore, extremely stringent requirements are placed on its mechanical properties, internal quality, and compositional uniformity.

[0003] Currently, sand casting remains the mainstream production process for end cap seat ring blanks in the industry. While sand casting offers adaptability to complex structural components and can meet the basic shape forming requirements of end cap seat rings, it has inherent limitations that are difficult to overcome in the manufacturing of core components for high-end equipment: First, during sand casting, factors such as sand mold permeability, the rationality of the gating system design, and the fluidity of the molten metal can easily lead to defects such as porosity, shrinkage, inclusions, and cracks inside the casting, directly affecting the structural integrity and mechanical performance stability of the end cap seat ring; Second, the solidification process in sand casting lacks effective control, resulting in coarse grains, significant compositional segregation, and poor microstructure uniformity in the casting, leading to large dispersion in mechanical properties and making it difficult to consistently meet the high standards required for high-end components; Third, the stability of the sand casting process is affected by multiple factors such as sand mold quality, binder ratio, pouring temperature, and cooling rate, resulting in large process fluctuations and making it difficult to effectively guarantee the product qualification rate.

[0004] Electroslag remelting (ESR) casting, as an advanced special casting technology, utilizes the resistance heat generated by current passing through molten slag to melt metal electrodes. The molten metal droplets are thoroughly purified as they pass through the slag layer, and the sequential solidification of the molten pool achieves component formation. It boasts significant technical advantages such as high metal purity (effectively removing harmful impurities like sulfur and phosphorus, as well as gases and inclusions), dense and uniform microstructure, strong near-net-shape forming capability, and small machining allowance. This fundamentally solves the quality defects inherent in sand-cast end cap rings. However, traditional ESR casting technology is primarily used for producing relatively simple steel ingots or regular components such as rolls, shafts, and discs. For core components like end cap rings with large semi-annular structures, a systematic ESR casting manufacturing method has not yet been developed. Key technical aspects such as process design, equipment adaptation, and quality control remain undeveloped. In particular, the unique structural shape of the end cap ring makes the arc-ignition process extremely difficult, and the quality of arc-ignition is hard to guarantee, severely impacting the forming effect and product quality of ESR casting. To this end, this application innovatively designs a targeted arc-initiating method, aiming to overcome this technical challenge and promote the large-scale application of electroslag casting technology in the field of high-end equipment manufacturing. Summary of the Invention

[0005] To address the challenges posed by the large cross-section of existing end cap seat rings, which makes arc initiation and slag formation difficult during electroslag casting, resulting in a stable liquid slag pool, poor forming quality of the arc initiation area, and easy slag inclusion, this invention provides an arc initiation device and method for electroslag casting end cap seat rings.

[0006] In a first aspect, the present invention provides an arc-initiating device for an electroslag casting end cap seat ring, comprising: The arc-initiating crystallization mechanism includes an arc-initiating slag-forming unit and a support unit arranged around the arc-initiating slag-forming unit. The inner wall of the support unit and the top surface of the arc-initiating slag-forming unit together form a first cavity with an upward opening. The top surface of the arc-initiating slag-forming unit is provided with an arc-initiating slag-forming section and a variable cross-section transition section in sequence along the flow direction of the slag pool. The inner diameter of the variable cross-section transition section tends to increase along the flow direction of the slag pool. The end cap seat ring main body crystallization mechanism has a second cavity with its opening facing downwards. The second cavity is adapted to the first cavity. The upper part of the end cap seat ring main body crystallization mechanism is also provided with a feeding opening that communicates with the second cavity. An arc-initiating electrode is provided in the second cavity. The arc-initiating electrode includes a first electrode and a second electrode. The first electrode and the second electrode are connected. The first electrode is adapted to the arc-initiating slag-forming section, and the second electrode is adapted to the variable cross-section transition section. A water-cooled heat dissipation unit is provided between the arc-initiating slag-forming unit and the support unit. The arc-initiating slag-forming unit is made of a first material, and the support unit is made of a second material. The thermal conductivity of the first material is higher than that of the second material.

[0007] In some embodiments, the sidewall of the arc-starting slag-forming section is arranged along the flow direction of the slag pool to form a first chamber. The inner length L1 of the first chamber is: L1=a×π / 4×(D1+D2), where D1 is the outer diameter of the end cap seat ring, D2 is the inner diameter of the end cap seat ring, and a is a first coefficient, 0.08≤a≤0.15.

[0008] In some embodiments, the inner cavity height H1 of the first chamber is: H1=b / 2×(D1-D2), where b is a second coefficient, 0.3≤b≤0.5.

[0009] In some embodiments, the sidewall of the variable cross-section transition section is arranged to form a second chamber along the flow direction of the slag pool. The extension direction of the second chamber is arc-shaped along the flow direction of the slag pool. The inner height H2 of the second chamber is: H2=(D1-L1 / 2)×tanγ, where γ is the transition angle, 10°≤γ≤30°.

[0010] In some embodiments, when the first electrode extends into the first chamber, the minimum gap between the first electrode and the first chamber is greater than or equal to 25 mm.

[0011] In some embodiments, the ratio k of the cross-sectional area of ​​the first electrode to the cross-sectional area of ​​the first chamber is in the range of 0.15 ≤ k ≤ 0.35.

[0012] In some embodiments, the height h2 of the second electrode is: h2 = d × H2, where d is a third coefficient, 2.5 ≤ b ≤ 3.5; The length of the second electrode increases along the flow direction of the slag pool.

[0013] In some embodiments, the water-cooled heat dissipation unit includes heat dissipation pipes that are connected to external coolant. When the heat dissipation pipes extend into a first chamber, a first heat-conducting section is formed. When the heat dissipation pipes extend into a second chamber, a second heat-conducting section is formed. When the heat dissipation pipes extend into a second cavity, a third heat-conducting section is formed. The coolant flows along the first heat-conducting section to the second heat-conducting section, then from the second heat-conducting section to the third heat-conducting section, and finally exits to the outside.

[0014] Secondly, the present invention provides an arc-starting method for an arc-starting device used in electroslag casting end cap seat rings, comprising: S1, Prepare an arc-initiating crystallization mechanism, so that the arc-initiating crystallization mechanism has an arc-initiating slag-forming section and a variable cross-section transition section; S2, prepare the main crystallization mechanism of the end cap seat ring, so that the first electrode of the arc-starting electrode is adapted to the arc-starting slag-forming section, and the second electrode of the arc-starting electrode is adapted to the variable cross-section transition section. S3, the arc ignition crystallization mechanism is coaxially connected with the main crystallization mechanism of the end cap seat ring, so that the first cavity and the second cavity are connected. The arc ignition electrode is hoisted to the top of the arc ignition crystallization mechanism and adjusted for centering. After filling the second cavity with solid slag through the feeding opening, the arc is ignited by power. After all the solid slag in the first cavity has melted to form a molten pool, the arc ignition electrode is controlled to descend to guide the molten pool to expand into the second cavity. Solid slag is continued to be filled through the feeding opening until the molten pool fills the preset position of the second cavity, thus completing the arc ignition process.

[0015] In some embodiments, the solid slag is composed of 70% CaF2 and 30% Al2O3. The initial filling amount of the solid slag is 60%-80% of the volume of the first chamber, and it is dried at 120°C for a drying time of 4 hours or more before filling.

[0016] In some embodiments, in step S3, the arc ignition adopts a stepped power increase mode: the initial voltage is set to 50-60V, the current is set to 1000-3000A, and after all the solid slag in the first chamber has dissolved to form a molten pool, the voltage is increased to 80-90V and then to 6000-8000A until the arc ignition process is completed.

[0017] To address the challenges posed by the large cross-section of existing end cap rings, which makes arc initiation and slag formation difficult during electroslag casting, resulting in a stable liquid slag pool, poor forming quality at the arc initiation point, and slag inclusions, this invention offers the following advantages: The technical solution of this invention utilizes an arc-initiating crystallization mechanism to form an arc-initiating slag-forming section and a variable cross-section transition section arranged sequentially along the slag pool flow direction at the bottom of the first cavity. This is combined with an arc-initiating electrode on the main crystallization mechanism of the end cap ring, ensuring that the first electrode of the arc-initiating electrode is adapted to the arc-initiating slag-forming section, and the second electrode is adapted to the variable cross-section transition section. Furthermore, a water-cooling heat dissipation unit is arranged between the arc-initiating slag-forming unit and the support unit. By employing a cold slag arc-initiating method, a stable and fully molten liquid slag pool is obtained, resulting in good arc-initiating quality. This leads to good bottom quality of the end cap ring casting while also saving costs. Attached Figure Description

[0018] Figure 1 A partial cross-sectional schematic diagram of an arc-initiating device for an electroslag casting end cap seat ring is shown; Figure 2 It shows Figure 1 A top view of the arc-initiating crystallization mechanism shown in the figure; Figure 3 It shows Figure 2A schematic diagram of the longitudinal cross-section of the inner cavity of the arc-initiating crystallization mechanism shown in the figure; Figure 4 It shows Figure 1 A partial structural schematic diagram of the arc-starting electrode shown in the figure; Figure 5 A flowchart of an arc-initiating method for an arc-initiating device used in electroslag casting end cap seat rings is shown.

[0019] Reference numerals: 10-Arc ignition device; 11-Arc ignition crystallization mechanism; 111-Arc ignition slag-forming unit; 1111-Arc ignition slag-forming section; 1112-Variable cross-section transition section; 112-Support unit; 113-First cavity; 1131-First chamber; 1132-Second chamber; 12-End cap seat ring main crystallization mechanism; 121-Feeding opening; 122-Second cavity; 13-Arc ignition electrode; 131-First electrode; 132-Second electrode; 14-Water cooling heat dissipation unit. Detailed Implementation

[0020] The present disclosure will now be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and thus implement the present disclosure, and are not intended to imply any limitation on the scope of the disclosure.

[0021] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment". The term "another embodiment" is to be interpreted as "at least one other embodiment". The terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments and are not intended to limit the indicated devices, elements, or components to having a specific orientation or being constructed and operated in a specific orientation. Furthermore, some of the above terms may be used to indicate other meanings besides orientations or positional relationships; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application according to the specific circumstances. In addition, the terms "installed", "set up", "equipped with", "connected", and "linked" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, elements, or components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. Furthermore, the terms "first," "second," etc., are mainly used to distinguish different devices, elements, or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0022] This embodiment discloses an arc-initiating device 10 for an electroslag casting end cap seat ring, such as... Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, the arc-initiating device 10 for electroslag casting end cap seat ring includes an arc-initiating crystallization mechanism 11 and an end cap seat ring main body crystallization mechanism 12.

[0023] Specifically, the arc-initiating crystallization mechanism 11 includes an arc-initiating slag-forming unit 111 and a support unit 112 arranged around the arc-initiating slag-forming unit 111. The inner sidewall of the support unit 112 and the top surface of the arc-initiating slag-forming unit 111 enclose a first cavity 113 with an upward opening. The top surface of the arc-initiating slag-forming unit 111 is provided with an arc-initiating slag-forming section 1111 and a variable cross-section transition section 1112 in sequence along the flow direction of the slag pool. The inner diameter of the variable cross-section transition section 1112 increases along the flow direction of the slag pool.

[0024] Specifically, a water-cooled heat dissipation unit 14 is arranged between the arc-ignition and slag-forming unit 111 and the support unit 112. The arc-ignition and slag-forming unit 111 is made of a first material, and the support unit 112 is made of a second material. The thermal conductivity of the first material is higher than that of the second material.

[0025] In this embodiment, an arc-initiating crystallization mechanism 11, i.e., a dedicated arc-initiating crystallizer, is designed and fabricated. This arc-initiating crystallizer is matched with the end cap ring main body crystallizer (i.e., the end cap ring main body crystallization mechanism 12). A support unit 112, made of a second material, supports the overall structural strength of the arc-initiating crystallization mechanism 11. An arc-initiating slag-forming unit 111, made of a first material, is formed, comprising an arc-initiating slag-forming section 1111 and a variable cross-section transition section 1112. A water-cooling heat dissipation unit 14, located between the first and second materials, is also included. This water-cooling heat dissipation unit 14 includes heat dissipation pipes connected to an external coolant, allowing the external coolant to carry away the heat absorbed by the first material during the electrical conduction and melting of the solid slag when the arc-initiating device 10 is energized. This heat is then quickly dissipated through the water-cooling heat dissipation unit 14, achieving a stable and fully molten liquid slag pool through cold slag arc initiation, resulting in good arc quality and a high-quality casting bottom, while also saving costs. In this application, the first material is preferably a steel structure, which can be formed by assembling and welding multiple steel plates; the second material is preferably a copper structure, which can be formed by extrusion casting.

[0026] In this embodiment, a first heat-conducting section is formed when the heat dissipation pipe extends to the first chamber 1131, a second heat-conducting section is formed when the heat dissipation pipe extends to the second chamber 1132, and a third heat-conducting section is formed when the heat dissipation pipe extends to the second cavity 122. The coolant flows along the first heat-conducting section to the second heat-conducting section, then from the second heat-conducting section to the third heat-conducting section, and finally exits to the outside. In this application, after absorbing a large amount of heat in the first heat-conducting section, the coolant passes through the second heat-conducting section. Since the temperature of the heat absorbed by the coolant in the first heat-conducting section is higher than the temperature of the dissolved solid slag in the second chamber 1132, when the coolant flows to the second heat-conducting section, the temperature of the coolant can further heat the dissolved liquid slag in the second chamber 1132. This prevents the liquid slag from cooling and solidifying due to prolonged flow, which would otherwise result in poor electroslag casting performance. Similarly, when the coolant flows from the second heat-conducting section to the third heat-conducting section, it can further heat the dissolved liquid slag in the second cavity 122, which can prevent the liquid slag from cooling and solidifying due to excessive flow time.

[0027] Specifically, the main crystallization mechanism 12 of the end cap seat ring can be made of steel structure, so that the inner cavity forms a hollow second cavity 122 with the opening facing downward. When the arc-initiating crystallization mechanism 11 is coaxially connected with the main crystallization mechanism 12 of the end cap seat ring, the second cavity 122 can be adapted to the first cavity 113 and form the cavity of the electroslag casting end cap seat ring.

[0028] Specifically, the main crystallization mechanism 12 of the end cap seat ring also includes an arc-starting electrode 13 located in the second cavity 122. By setting the arc-starting electrode 13 as a first electrode 131 and a second electrode 132 that are mutually conductive, the first electrode 131 is adapted to the arc-starting slag-forming section 1111, and the second electrode 132 is adapted to the variable cross-section transition section 1112. This allows the arc-starting electrode 13 to be hoisted to the top of the arc-starting crystallizer and adjusted for centering when the arc-starting crystallization mechanism 11 and the main crystallization mechanism 12 of the end cap seat ring are coaxially connected. After filling the arc-starting slag-forming section 1111 with solid slag, the arc is started by energizing. After the slag pool forms a stable molten pool, the arc-starting electrode 13 is controlled to descend to guide the slag pool to expand into the main crystallizer until the slag pool in the transition section is completely fused with the main crystallizer, thus completing the arc-starting process.

[0029] Furthermore, the sidewall of the arc-starting and slag-forming section 1111 is arranged along the flow direction of the slag pool to form a first chamber 1131, which satisfies the following conditions: (1) The inner width of the first chamber 1131 is equal to the wall thickness of the end cap seat ring casting. The wall thickness is 1 / 2 of the difference between the outer diameter D1 and the inner diameter D2 of the semi-circular ring structure at the bottom of the end cap seat ring, that is, the width W = (D1-D2) / 2. (2) The inner length of the first chamber 1131 is crucial. If the length is too long, the arc initiation section will be too large, resulting in poor arc initiation quality. If the length is too short, the slag pool will not be completely melted due to the good cooling effect, and production operation will be difficult. Therefore, the inner length L1 can be calculated according to the formula L1=a×π / 4×(D1+D2), where a is the first coefficient, and its value range is preferably 0.08-0.15. (3) The height of the inner cavity of the first chamber 1131 is also important. If the height is too low, the slag will reach the transition stage of the variable cross section before it is completely melted, which will affect the arc ignition effect. If the height is too high, it will increase the manufacturing cost of the crystallizer and the electrode, which is not conducive to actual industrial production. The inner cavity height H1 is calculated according to the formula H1=b / 2×(D1-D2), where b is the second coefficient, and its value range is preferably 0.3-0.5.

[0030] Furthermore, the sidewall of the variable cross-section transition section 1112 forms a second chamber 1132 along the flow direction of the slag pool, and the extension direction of the second chamber 1132 is arc-shaped along the flow direction of the slag pool. In this application, the variable cross-section transition section 1112 of the arc-initiating crystallization mechanism 11 is preferably wedge-shaped, satisfying the following conditions: (1) The inner cavity height H2 of the second chamber 1132 can be calculated according to the formula H2=(D1-L1 / 2)×tanγ, where γ is the transition angle, and its value range is preferably 10°-30°, and L1 is the inner cavity length of the arc-starting slag-forming section 1111; (2) The bottom of the variable cross-section transition section 1112 is completely fitted with the inner cavity cross-section of the arc-starting and slag-forming section 1111, and the top of the variable cross-section transition section 1112 is consistent with the bottom cross-sectional profile of the end cap seat ring main crystallization mechanism 12. In this application, the first chamber 1131 and the second chamber 1132 together constitute the first cavity 113.

[0031] Furthermore, the first electrode 131 of the arc-starting electrode 13 must meet the following conditions: (1) The cross-sectional shape is square, which matches the first chamber 1131 of the arc ignition and slag-forming section 1111 of the arc ignition crystallization mechanism 11; (2) The transverse cross-sectional dimension of the first electrode 131 is smaller than the inner cavity dimension of the first chamber 1131, and when the first electrode 131 is inserted into the first chamber 1131, the minimum gap formed between the side wall of the first electrode 131 and the inner side wall of the first chamber 1131 is greater than or equal to 25 mm. (3) The filling ratio k between the first electrode 131 and the inner cavity of the first chamber 1131 is 0.15-0.35. This filling ratio k is the ratio of the cross-sectional area of ​​the first electrode 131 to the cross-sectional area of ​​the first chamber 1131. (4) The electrode weight is 1.1 times its theoretical weight. The theoretical weight is calculated based on the electrode material density and electrode volume. The electrode height h1 is calculated from the cross-sectional area of ​​the first electrode 131 and the weight of the first electrode 131, which is not detailed in this application.

[0032] Furthermore, the second electrode 132 of the arc-starting electrode 13 must meet the following conditions: (1) The bottom cross section of the second electrode 132 is completely connected to the square cross section of the first electrode 131, and the top cross section of the second electrode 132 is consistent with the cross section of the main electrode of the end cap seat ring body casting. (2) The cross-sectional area of ​​the second electrode 132 gradually increases along the flow direction of the slag pool; (3) The height h2 of the second electrode 132 is calculated according to the formula h2=d×H2, where d is the third coefficient, the preferred value range is 2.5-3.5, and H2 is the inner height of the second chamber 1132; (4) The maximum length (or shape) of the second electrode 132 is determined by the electrode corresponding to the main crystallizer, which is not detailed in this application.

[0033] In this embodiment, the arc-starting electrode 13 is manufactured by casting or plate welding.

[0034] This embodiment also discloses an arc-initiating device 10 and an arc-initiating method for an electroslag casting end cap seat ring, such as... Figure 5 As shown, the method steps include: S1, Prepare the arc-initiating crystallization mechanism 11, so that the arc-initiating crystallization mechanism 11 has an arc-initiating slag-forming section 1111 and a variable cross-section transition section 1112; S2, prepare the main crystallization mechanism 12 of the end cap seat ring, so that the first electrode 131 of the arc-starting electrode 13 is adapted to the arc-starting slag-forming section 1111, and the second electrode 132 of the arc-starting electrode 13 is adapted to the variable cross-section transition section 1112. S3, the arc-ignition crystallization mechanism 11 is coaxially connected with the end cap seat ring main body crystallization mechanism 12, so that the first cavity 113 and the second cavity 122 are connected. The arc-ignition electrode 13 is hoisted to the top of the arc-ignition crystallization mechanism 11 and adjusted for centering. After filling the second cavity 122 with solid slag through the feeding opening 121, the arc is ignited by electricity. After all the solid slag in the first cavity 1131 has melted to form a molten pool, the arc-ignition electrode 13 is controlled to descend to guide the molten pool to expand into the second cavity 1132. Solid slag is continued to be filled through the feeding opening 121 until the molten pool fills the preset position of the second cavity 122, thus completing the arc-ignition process.

[0035] Furthermore, in step S3, the arc ignition adopts a stepped power increase mode: the initial voltage is set to 50-60V, and the current is set to 1000-3000A. After all the solid slag in the first chamber 1131 has melted to form a molten pool, the voltage is increased to 80-90V and then to 6000-8000A until the arc ignition process is completed. In this application, at the beginning of arc ignition, only the solid slag in the first chamber 1131 needs to be melted by electrical conduction and heat conduction.

[0036] Furthermore, the solid slag is composed of 70% CaF2 and 30% Al2O3. The initial filling amount of the solid slag is 60%-80% of the inner volume of the first chamber 1131, and it is dried at 120°C before filling for a drying time of 4 hours or more.

[0037] In this embodiment, by taking advantage of the high metal purity, good sequential solidification characteristics, and strong near-net-shape forming ability of electroslag casting technology through the above steps, defects such as porosity, shrinkage porosity, and slag inclusions caused by sand casting are avoided, thereby improving the quality stability of the product.

[0038] Secondly, by independently designing the arc-initiating crystallization mechanism 11 and the arc-initiating electrode 13, a stable and fully molten liquid slag pool is obtained by using cold slag arc initiation, resulting in good arc initiation quality, thus ensuring good bottom quality of the casting, while also saving costs.

[0039] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0040] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. An arc-starting device for an electroslag casting end cap seat ring, characterized in that, include: The arc-initiating crystallization mechanism includes an arc-initiating slag-forming unit and a support unit arranged around the arc-initiating slag-forming unit. The inner wall of the support unit and the top surface of the arc-initiating slag-forming unit together form a first cavity with an upward opening. The top surface of the arc-initiating slag-forming unit is provided with an arc-initiating slag-forming section and a variable cross-section transition section in sequence along the flow direction of the slag pool. The inner diameter of the variable cross-section transition section tends to increase along the flow direction of the slag pool. The end cap seat ring main body crystallization mechanism has a second cavity with its opening facing downwards. The second cavity is adapted to the first cavity. The upper part of the end cap seat ring main body crystallization mechanism is also provided with a feeding opening that communicates with the second cavity. An arc-initiating electrode is provided in the second cavity. The arc-initiating electrode includes a first electrode and a second electrode. The first electrode and the second electrode are connected. The first electrode is adapted to the arc-initiating slag-forming section, and the second electrode is adapted to the variable cross-section transition section. A water-cooled heat dissipation unit is provided between the arc-initiating slag-forming unit and the support unit. The arc-initiating slag-forming unit is made of a first material, and the support unit is made of a second material. The thermal conductivity of the first material is higher than that of the second material.

2. The arc-starting device for electroslag casting end cap seat ring as described in claim 1, characterized in that, The sidewall of the arc-starting slag-forming section is arranged along the flow direction of the slag pool to form a first chamber. The inner length L1 of the first chamber is: L1=a×π / 4×(D1+D2), where D1 is the outer diameter of the end cap seat ring, D2 is the inner diameter of the end cap seat ring, and a is the first coefficient, 0.08≤a≤0.

15.

3. The arc-starting device for the end cap seat ring of electroslag casting as described in claim 2, characterized in that, The value of the inner cavity height H1 of the first chamber is: H1=b / 2×(D1-D2), where b is the second coefficient, 0.3≤b≤0.

5.

4. The arc-starting device for electroslag casting end cap seat ring as described in claim 3, characterized in that, The sidewall of the variable cross-section transition section is arranged along the flow direction of the slag pool to form a second chamber. The extension direction of the second chamber is arc-shaped along the flow direction of the slag pool. The inner height H2 of the second chamber is: H2=(D1-L1 / 2)×tanγ, where γ is the transition angle, 10°≤γ≤30°.

5. The arc-starting device for an electroslag casting end cap seat ring as described in claim 2 or 3, characterized in that, When the first electrode is inserted into the first chamber, the minimum gap between the first electrode and the first chamber is greater than or equal to 25 mm.

6. The arc-starting device for an electroslag casting end cap seat ring as described in claim 2 or 3, characterized in that, The value range of k, which is the ratio of the cross-sectional area of ​​the first electrode to the cross-sectional area of ​​the first chamber, is: 0.15≤k≤0.

35.

7. The arc-starting device for an electroslag casting end cap seat ring as described in claim 4, characterized in that, The height h2 of the second electrode is: h2 = d × H2, where d is the third coefficient, 2.5 ≤ b ≤ 3.5; The length of the second electrode increases along the flow direction of the slag pool.

8. The arc-starting device for an electroslag casting end cap seat ring as described in claim 4, characterized in that, The water-cooled heat dissipation unit includes heat dissipation pipes that are connected to external coolant. When the heat dissipation pipes extend into the first chamber, they form a first heat-conducting section. When the heat dissipation pipes extend into the second chamber, they form a second heat-conducting section. When the heat dissipation pipes extend into the second cavity, they form a third heat-conducting section. The coolant flows along the first heat-conducting section to the second heat-conducting section, then from the second heat-conducting section to the third heat-conducting section, and finally exits to the outside.

9. An arc-starting method applied to the arc-starting device for electroslag casting end cap seat rings as described in any one of claims 1-8, characterized in that, include: S1, Prepare an arc-initiating crystallization mechanism, so that the arc-initiating crystallization mechanism has an arc-initiating slag-forming section and a variable cross-section transition section; S2, prepare the main crystallization mechanism of the end cap seat ring, so that the first electrode of the arc-starting electrode is adapted to the arc-starting slag-forming section, and the second electrode of the arc-starting electrode is adapted to the variable cross-section transition section. S3, the arc ignition crystallization mechanism is coaxially connected with the main crystallization mechanism of the end cap seat ring, so that the first cavity and the second cavity are connected. The arc ignition electrode is hoisted to the top of the arc ignition crystallization mechanism and adjusted for centering. After filling the second cavity with solid slag through the feeding opening, the arc is ignited by power. After all the solid slag in the first cavity has melted to form a molten pool, the arc ignition electrode is controlled to descend to guide the molten pool to expand into the second cavity. Solid slag is continued to be filled through the feeding opening until the molten pool fills the preset position of the second cavity, thus completing the arc ignition process.

10. The arc-initiating method as described in claim 9, characterized in that, include: The solid slag is composed of 70% CaF2 and 30% Al2O3. The initial filling amount of the solid slag is 60%-80% of the volume of the first chamber, and it is dried at 120°C for at least 4 hours before filling.

11. The arc-initiating method as described in claim 9, characterized in that, include: In step S3, the arc ignition adopts a stepped power increase mode: the initial voltage is set to 50-60V and the current is set to 1000-3000A. After all the solid slag in the first chamber has melted to form a molten pool, the voltage is increased to 80-90V and then to 6000-8000A until the arc ignition process is completed.

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