Electric arc furnace capable of reliably driving furnace cover

Abstract

The utility model relates to an electric arc furnace capable of reliably driving a furnace cover, which comprises a furnace body and a large furnace cover, the large furnace cover is provided with a rotary driving mechanism and a large furnace cover lifting mechanism, the rotary driving mechanism comprises a rotary frame and a rotary driving unit, and the large furnace cover lifting mechanism comprises a lifting frame and a large furnace cover lifting power unit arranged on the rotary frame. A first butt joint matching unit is arranged on the lifting frame, a second butt joint matching unit is arranged on the large furnace cover, and the first butt joint matching unit and the second butt joint matching unit are coupled or separated along with lifting of the lifting frame. According to the electric arc furnace, the rotary driving mechanism is coupled with the large furnace cover lifting mechanism, so that the operation flexibility of the electric arc furnace can be improved; the first butt joint matching unit on the lifting frame is matched with the second alignment matching unit on the large furnace cover, coupling or separation of the large furnace cover and the lifting frame is easily achieved, it is guaranteed that the large furnace cover is stably driven, operation is easy, the mechanical matching relation is achieved, and reliability is high.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the electric furnace steelmaking technical field, concretely relates to an electric arc furnace capable of reliably driving a furnace cover. BACKGROUND

[0002] At present, the electric arc furnace equipment form tends to be mature and fixed, and is basically evolved from the top charging electric furnace, the shaft furnace and the horizontal charging electric furnace and other forms. The electric arc furnace generally comprises a furnace body and a furnace cover, and the furnace cover can be separated from the furnace body, so that a rotary drive mechanism and a lifting drive mechanism are generally configured for the furnace cover. The lifting drive mechanism mainly has two structural forms: (1) a furnace cover lifting oil cylinder + chain wheel-chain mode is adopted, and the lifting drive mechanism is generally installed on the rotating frame of the rotary drive mechanism. This mode causes problems such as large on-site equipment, large occupied space, and great difficulty in equipment maintenance; (2) a furnace cover lifting oil cylinder + lifting column mode is adopted, and two groups of furnace cover lifting oil cylinders + lifting columns are generally arranged on the rack platform / tilting platform. In this mode, the lifting and rotation of the furnace cover are separated, and the flexibility is relatively insufficient, the number of oil cylinders is relatively large, and the occupied space is relatively large. SUMMARY

[0003] The utility model relates to an electric arc furnace capable of reliably driving a furnace cover, and at least solves some defects of the prior art.

[0004] The utility model relates to an electric arc furnace capable of reliably driving a furnace cover, and at least solves some defects of the prior art.

[0005] As one of the implementation manners, the first docking cooperation unit comprises a positioning top head and a jacking support plate, the positioning top head is arranged at the top end of the lifting frame, and the jacking support plate is arranged at one end of the lifting frame close to the furnace body; the second docking cooperation unit comprises a jacking positioning hole and a jacking support plate arranged on the large furnace cover, wherein the jacking positioning hole is located directly above the positioning top head, and the jacking support plate is located directly above the jacking support plate; when the positioning top head is clamped into the positioning hole, the jacking support plate and the jacking support plate abut.

[0006] As one of the implementation manners, a support arm is arranged on the large furnace cover, and the second docking cooperation unit is arranged on the support arm.

[0007] As one of the embodiments, a lifting frame guide structure is arranged on the rotating frame to prevent the lifting frame from swinging when the lifting frame is lifted.

[0008] As one of the embodiments, the rotating frame is a hollow structure.

[0009] As one of the embodiments, the electric arc furnace further comprises an electrode lifting driving mechanism, the electrode lifting driving mechanism comprising a lifting column and an electrode lifting driving cylinder for driving the lifting column to lift, the lifting column being mounted in the rotating frame and having a top end extending out of the top end of the rotating frame to mount the conductive cross arm.

[0010] As one of the embodiments, a column guide structure is arranged in the rotating frame to prevent the lifting column from swinging when the lifting column is lifted.

[0011] As one of the embodiments, an annular sealing wall is upwardly protruded on the large furnace cover, an annular slot is arranged in the small furnace cover and is recessed upwardly from the bottom surface of the small furnace cover, the annular sealing wall is inserted into the annular slot, the slot width of the annular slot is greater than the thickness of the annular sealing wall, and the difference between the slot width and the thickness is designed to prevent the annular sealing wall from interfering with the small furnace cover when the large furnace cover tilts.

[0012] As one of the embodiments, the slot depth of the annular slot is not less than the height of the annular sealing wall.

[0013] As one of the embodiments, the annular sealing wall is an elliptical annular wall, the annular slot is an elliptical annular slot, and the long axis directions of the annular sealing wall and the annular slot are parallel to the front-to-rear line direction of the furnace.

[0014] The utility model has at least the following beneficial effects:

[0015] In the utility model, the rotary driving mechanism is coupled with the large furnace cover lifting mechanism, the large furnace cover can be lifted only, the large furnace cover can be lifted and rotated, and the operation flexibility of the electric arc furnace is improved, the interference between the large furnace cover and the furnace body during the rotation of the large furnace cover is reduced, the first docking unit on the lifting frame and the second alignment unit on the large furnace cover are matched, the large furnace cover and the lifting frame are coupled or separated, the large furnace cover is stably driven, the operation is easy, and the mechanical matching relationship is reliable. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0017] Figure 1 The structure schematic diagram of the electric arc furnace provided by the embodiment of the present application is provided.

[0018] Figure 2 The top view (including two states of large furnace cover) of the electric arc furnace provided by the embodiment of the present application is provided.

[0019] Figure 3 The tilting state schematic diagram of the electric arc furnace provided by the embodiment of the present application is provided.

[0020] Figure 4 The structure schematic diagram of the large furnace cover lifting mechanism and the small furnace cover lifting mechanism provided by the embodiment of the present application is provided.

[0021] Figure 5 The cooperation schematic diagram of the lifting hook and the lifting ring is provided.

[0022] Figure 6 The cooperation schematic diagram of the cross-section guide rod and the guide hole is provided. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0024] As Figures 1-4 The embodiment of the present application provides an electric arc furnace capable of reliably driving a furnace cover, which comprises a furnace body 11 and a large furnace cover 12. The large furnace cover 12 and the furnace body 11 are designed as a separable connection structure, so as to facilitate the operation of maintenance and the like of the large furnace cover 12 and the furnace body 11. The large furnace cover 12 is provided with a lifting structure, so that it can be lifted.

[0025] In one of the embodiments, the large furnace cover 12 is a frame type water cooling structure, and a plurality of water cooling plates are hung on a water cooling frame. The water cooling frame is not only a structure support, but also a channel for water supply and drainage of the water cooling plates.

[0026] Furthermore, as shown in the figure, it also includes a small furnace cover 13, which is provided with electrode holes for electrodes 21 to pass through. Generally, there are three electrodes 21, which are arranged in a triangle. Correspondingly, there are three electrode holes, which are also arranged in a triangle.

[0027] Preferably, the furnace body 11 has an eccentric structure, with the tapping port located in the eccentric area, enabling slag-free tapping. Optionally, the lower half of the furnace body 11 is lined with refractory material to protect the furnace body 11 during steelmaking; the upper half of the furnace body 11 is equipped with a water-cooled furnace wall (water-cooled) to extend the service life of the furnace body 11.

[0028] Preferably, the furnace body 11 is connected to a tilting mechanism 14. Optionally, the tilting mechanism 14 includes a tilting platform and a tilting cylinder 141. The furnace body 11 is mounted on the tilting platform, preferably by means of a positioning pin on the upper surface of the tilting platform. The tilting platform is movably mounted on the workshop foundation, including but not limited to an arc-shaped support frame 143 on each side of the bottom of the tilting platform. Each arc-shaped support frame 143 is supported by a rotating wheel 142 fixed on the workshop foundation. The cylinder body of the tilting cylinder 141 is hinged to the workshop foundation, and the output end of the tilting cylinder 141 is hinged to the tilting platform. Driven by the tilting cylinder 141, the entire tilting platform can rotate relative to the workshop foundation, ultimately achieving rapid steel tapping and exposing the steel tapping port inside the furnace for sand filling, etc.

[0029] Preferably, the large furnace cover 12 is equipped with a rotary drive mechanism for driving the large furnace cover 12 to rotate in the horizontal plane, which can make the large furnace cover 12 peel off from the furnace body 11 or cover the furnace body 11. The rotary drive mechanism is set on the workshop foundation and does not need to be tilted together with the tilting platform. Therefore, it can effectively reduce the difficulty of tilting and reduce the requirements for equipment such as the tilting platform and tilting cylinder 141, thereby reducing costs and improving production safety.

[0030] like Figure 1 The rotary drive mechanism includes a rotating frame 20 and a rotary drive unit for driving the rotating frame 20 to rotate. The rotating frame 20 is rotatably mounted on a workshop foundation, including but not limited to a slewing bearing 24 installed on the workshop foundation. The slewing bearing 24 includes a rotatably fitted outer bearing ring and an inner bearing ring, and the rotating frame 20 is connected to the outer bearing ring or the inner bearing ring. The rotary drive unit can be a conventional rotary drive device, which will not be exemplified here.

[0031] Generally, electrode 21 is equipped with an electrode lifting drive mechanism, which allows for real-time adjustment of the height of electrode 21. Preferably, as follows: Figure 1The electrode lifting driving mechanism comprises a lifting column 23 and an electrode lifting driving cylinder 25 for driving the lifting column 23 to lift, and the electrode 21 is installed on the lifting column 23 through a conductive cross arm 22, the conductive cross arm 22 is lifted by the lifting column 23, and then the electrode 21 is lifted. In one embodiment, as shown in Figure 1 The rotating frame 20 is a hollow structure, the lifting column 23 is installed in the rotating frame 20, the bottom end of the lifting column 23 extends out of the bottom end of the rotating frame 20 and is connected with the electrode lifting driving cylinder 25, and the top end of the lifting column 23 extends out of the top end of the rotating frame 20 to facilitate installation of the conductive cross arm 22. Further, in order to ensure that the electrode 21 can be lifted vertically and avoid damage caused by mutual collision and friction between the electrode 21 and the electrode hole, a column guiding structure can be arranged in the rotating frame 20 to ensure that the lifting column 23 does not swing when it is lifted up and down, and the column guiding structure includes but is not limited to a plurality of guide wheels that guide and cooperate with the lifting column 23.

[0032] Preferably, the rotary driving mechanism is detachably coupled with the large furnace cover 12, which can improve the operation flexibility of the electric arc furnace, for example, after the rotary driving mechanism is separated from the large furnace cover 12, the large furnace cover 12 can be conveniently tilted with the furnace body 11.

[0033] In one embodiment, as shown in Figure 1 , Figure 2 and Figure 4 The rotating frame 20 of the rotary driving mechanism is provided with a large furnace cover lifting mechanism, which is detachably coupled with the large furnace cover 12, that is, the detachable coupling relationship between the rotary driving mechanism and the large furnace cover 12 can be realized through the large furnace cover lifting mechanism; by configuring the large furnace cover lifting mechanism, the operations of lifting only the large furnace cover 12 and lifting and rotating the large furnace cover 12 can be realized, thereby improving the operation flexibility of the electric arc furnace and reducing the interference between the large furnace cover 12 and the furnace body 11 during rotation.

[0034] In one embodiment, as shown in Figure 1 and Figure 4The large furnace cover lifting mechanism comprises a lifting frame 26 and a large furnace cover lifting power unit 260 for driving the lifting frame 26 to lift, and the large furnace cover lifting power unit 260 is installed on the rotating frame 20; the lifting frame 26 is provided with a first docking and matching unit, and the large furnace cover 12 is provided with a second docking and matching unit, and the lifting frame 26 can drive the first docking and matching unit to couple or separate from the second docking and matching unit under the driving of the large furnace cover lifting power unit 260, and after the first docking and matching unit and the second docking and matching unit are coupled, the connection between the lifting frame 26 and the large furnace cover 12 is realized, and when the lifting frame 26 further rises, the large furnace cover 12 can be lifted, and when the lifting frame 26 descends, the large furnace cover 12 can be lowered, until the first docking and matching unit and the second docking and matching unit are separated, at which time the separation between the lifting frame 26 and the large furnace cover 12 is realized.

[0035] Optionally, as Figure 4 , the first docking and matching unit comprises a positioning top head 262 and a jacking support plate 261, the positioning top head 262 is arranged at the top end of the lifting frame 26, and the jacking support plate 261 is arranged at one end of the lifting frame 26 close to the furnace body 11; correspondingly, the second docking and matching unit comprises a jacking positioning hole 152 and a jacking support plate 151 arranged on the large furnace cover 12, wherein the jacking positioning hole 152 is located directly above the positioning top head 262, and the jacking support plate 151 is located directly above the jacking support plate 261, when the positioning top head 262 is clamped into the positioning hole, the jacking support plate 261 abuts against the jacking support plate 151, so that the coupling between the lifting frame 26 and the large furnace cover 12 can be realized. As Figure 1 、 Figure 2 and Figure 4 , the support arm 15 can be arranged on the large furnace cover 12, and the jacking positioning hole 152 and the jacking support plate 151 are arranged on the support arm 15, which can facilitate the coupling and separation between the lifting frame 26.

[0036] Preferably, the lifting frame guide structure 263 can be arranged on the rotating frame 20 to ensure that the lifting frame does not swing when it rises and falls, and the lifting frame guide structure 263 comprises but is not limited to a guide column and a guide wheel cooperation mode, the guide column can be arranged on the lifting frame and guided and matched with the guide wheel arranged on the rotating frame 20.

[0037] The above-mentioned large furnace cover lifting power unit 260 comprises but is not limited to a hydraulic cylinder, and one or more sets of large furnace cover lifting power units 260 can be arranged.

[0038] In one embodiment, as Figures 1-4The large furnace cover 12 has an annular sealing wall 120 protruding upwards, and the small furnace cover 13 has an annular slit groove 130. The annular slit groove 130 is formed by an upward indentation from the bottom surface of the small furnace cover 13. The annular sealing wall 120 is inserted into the annular slit groove 130. The width of the annular slit groove 130 is greater than the thickness of the annular sealing wall 120, and the difference between the two is designed so that the annular sealing wall 120 does not interfere with the small furnace cover 13 when the large furnace cover 12 is tilted.

[0039] In one embodiment, such as Figure 2 The annular sealing wall 120 is an elliptical annular wall, and the annular slit groove 130 is an elliptical annular groove. The major axis of both is parallel to the line connecting the front and rear of the furnace. Based on this design, the relative movement requirements between the annular sealing wall 120 and the annular slit groove 130 can be better met, and the interference between them can be reduced.

[0040] The width of the straight section of the annular slit groove 130 can be slightly larger than the thickness of the straight section of the annular sealing wall 120. For example, the straight section groove and the straight section wall can be fitted with a gap to reduce the amount of flue gas leaking between them. The gap fit between them can also achieve a guiding fit, which can improve the stability and accuracy of the relative movement between the annular sealing wall 120 and the annular slit groove 130.

[0041] The arc-shaped section of the annular slit groove 130 preferably has a uniform groove width, and the arc-shaped section of the annular sealing wall 120 preferably has a uniform thickness. The difference between the groove width of the arc-shaped section and the thickness of the arc-shaped section satisfies the requirement that "the annular sealing wall 120 does not interfere with the small furnace cover 13 when the large furnace cover 12 is tilted". This difference is related to factors such as the tilting angle of the furnace body 11, and is preferably controlled within the range of 50 to 100 mm.

[0042] In one embodiment, such as Figure 3 and Figure 4 The inner ring of the annular slit groove 130 is chamfered. In the above-mentioned scheme using an elliptical annular groove, at least the inner ring of the arc-shaped groove is chamfered. This further reduces interference between the annular sealing wall 120 and the annular slit groove 130 during tilting. Furthermore, the inner ring root of the annular sealing wall 120 is thickened to form a bevel, facilitating its fit with the chamfered groove and ensuring a labyrinth seal effect between the annular slit groove 130 and the annular sealing wall 120.

[0043] Preferably, the depth of the annular slit groove 130 is not less than the height of the annular sealing wall 120, which can ensure that the bottom end of the small furnace cover 13 is fastened to the top end of the large furnace cover 12 in a non-tilting state, thus ensuring a tight seal.

[0044] In one embodiment, the small furnace cover 13 is configured with a small furnace cover lifting mechanism 27; optionally, as Figure 1 、 Figure 2 and Figure 4 , the small furnace cover lifting mechanism 27 is arranged on the rotating frame 20 of the rotary drive mechanism, which can facilitate the arrangement of the small furnace cover lifting mechanism 27 and the relevant operation of the small furnace cover 13, such as allowing the small furnace cover 13 to rotate with the rotating frame 20. Further, the small furnace cover lifting mechanism 27 is detachably connected with the small furnace cover 13, which can improve the flexibility of the operation of the electric arc furnace.

[0045] In one embodiment, as Figures 1-5 , the small furnace cover lifting mechanism 27 includes a lifting hook 273 and a small furnace cover lifting power unit for driving the lifting hook 273 to lift, and the lifting hook 273 is preferably provided in multiple numbers, which can improve the stability of the lifting of the small furnace cover 13, and correspondingly a plurality of lifting rings are provided on the small furnace cover 13. It is preferred to design the lifting ring hole 131 to have a relatively large height (for example, an oval lifting ring hole 131 is adopted), so as to ensure that the lifting hook 273 can freely enter and exit the lifting ring hole 131, for example, the height of the lifting ring hole 131 is greater than the hook body height h of the lifting hook 273.

[0046] Preferably, as Figure 1 、 Figure 4 and Figure 6 , a lifting hook guide unit 274 is arranged on the rotating frame 20 to ensure that the lifting hook 273 does not rotate during lifting, thereby ensuring that the lifting hook 273 can reliably hook the lifting ring on the small furnace cover 13 each time; the lifting hook guide unit 274 includes but is not limited to a guide rod 2741-guide hole 2742 cooperation form, for example, a guide hole 2742 is formed on the rotating frame 20, and a guide rod 2741 is fixedly connected at the top end of the lifting hook 273, which is guided and cooperated by the guide rod 2741 and the guide hole 2742 to achieve the purpose of ensuring that the lifting hook 273 does not rotate during lifting; further, as Figure 6 , the guide rod 2741 and the guide hole 2742 adopt a cross-section, which is better in guiding and restraining the lifting hook 273.

[0047] Optionally, as Figure 4 , the small furnace cover lifting power unit adopts a soft chain 272 cooperated with a pulley, which can facilitate the arrangement of these power devices, and the soft chain 272 can adopt a chain, a steel wire rope, etc.; the power device 271 connected by the soft chain 272 can be a hydraulic cylinder, an air cylinder, etc. linear driving device.

[0048] The embodiment also provides an operation method of the above-mentioned electric arc furnace, comprising:

[0049] When the tapping is needed, the small furnace cover 13 is lifted to a set height, the furnace body 11 is tilted to tap by the tilting mechanism 14, the large furnace cover 12 is tilted with the furnace body 11 and drives the annular sealing wall 120 to rotate relative to the small furnace cover 13, wherein the annular sealing wall 120 does not interfere with the small furnace cover 13, and the annular sealing wall 120 does not come out of the annular gap slot 130;

[0050] After the tapping is completed, the furnace body 11 and the small furnace cover 13 are reset.

[0051] In the above tapping operation, the electrode 21 and the matching facilities (the conductive cross arm 22, the lifting column 23, etc.), the rotary drive mechanism (including the rotating frame 20, the rotary support 24) and the like do not need to be tilted, so that the tilting tapping operation is significantly simplified, and the safety of the tapping operation is ensured.

[0052] Further, based on the above electric arc furnace, the operation method further comprises:

[0053] When the electrode 21 needs to be replaced or reformed, each electrode 21 is driven to be lifted to a high position, the lifting column 23, the conductive cross arm 22 and the electrode 21 are driven to be turned to the tapping side by driving the rotating frame 20, and the electrode 21 is replaced or reformed. In the process of turning the electrode 21, the small furnace cover lifting mechanism 27 is separated from the small furnace cover 13 (for example, see Figure 5 The hook 273 is in the lowest position, and when the hook 273 rotates with the rotating frame 20, it is separated from the lifting ring, so that the small furnace cover 13 is prevented from rotating with the electrode 21. At this time, the small furnace cover 13 or the large furnace cover 12 can also be lifted to the maintenance and repair area by the travelling crane.

[0054] Further, based on the above electric arc furnace, the operation method further comprises:

[0055] When the large furnace cover 12 needs to be replaced, the small furnace cover 13 is lifted to the highest point by the small furnace cover lifting mechanism 27, the small furnace cover 13 is completely separated from the large furnace cover 12, and then the rotating frame 20 is driven to rotate, the electrode 21 is turned to the tapping side together with the small furnace cover 13, and the large furnace cover 12 can be lifted to the maintenance area by the travelling crane.

[0056] Further, based on the above electric arc furnace, the operation method further comprises:

[0057] When the furnace body 11 needs to be replaced or repaired, the large furnace cover lifting mechanism is actuated to lift the large furnace cover 12, and since the small furnace cover 13 is placed on the large furnace cover 12, the small furnace cover 13 is also lifted together; when the large furnace cover 12 is lifted to a high position, the rotating frame 20 is driven to rotate, the large furnace cover 12, the small furnace cover 13, the electrode 21 and the conductive cross arm 22 and the like are rotated to the tapping side, and the furnace body 11 is lifted to the maintenance area by the travelling crane.

[0058] The above merely describes preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An electric arc furnace capable of reliably driving a roof, comprising a furnace body and a large roof, the large roof being provided with a slewing drive mechanism, the slewing drive mechanism comprising a slewing frame and a slewing drive unit for driving the slewing frame to rotate, characterized in that: The large furnace cover is further provided with a large furnace cover lifting mechanism, which comprises a lifting frame and a large furnace cover lifting power unit for driving the lifting frame to lift, the large furnace cover lifting power unit is installed on the rotating frame, a first docking and matching unit is arranged on the lifting frame, a second docking and matching unit is arranged on the large furnace cover, and the first docking and matching unit and the second docking and matching unit are adapted to be coupled or separated within the lifting stroke range of the lifting frame.

2. The electric arc furnace with reliably drivable furnace covers as claimed in claim 1, characterized in that The first docking and matching unit comprises a positioning top head and a jacking support plate, the positioning top head is arranged at the top end of the lifting frame, and the jacking support plate is arranged at one end of the lifting frame close to the furnace body; the second docking and matching unit comprises a jacking positioning hole and a jacking support plate arranged on the large furnace cover, wherein the jacking positioning hole is located directly above the positioning top head, and the jacking support plate is located directly above the jacking support plate, and when the positioning top head is clamped into the positioning hole, the jacking support plate abuts against the jacking support plate.

3. An electric arc furnace with reliably drivable furnace covers according to claim 1 or 2, characterized in that: A support arm is arranged on the large furnace cover.

4. The electric arc furnace with reliably drivable furnace covers as claimed in claim 1, characterized in that A lifting frame guide structure is arranged on the rotating frame to prevent the lifting frame from swinging when lifting.

5. The electric arc furnace with reliably drivable furnace covers as claimed in claim 1, characterized in that The rotating frame is a hollow structure.

6. The electric arc furnace with reliably drivable furnace covers as claimed in claim 5, characterized in that Further comprising an electrode lifting driving mechanism, the electrode lifting driving mechanism comprises a lifting column and an electrode lifting driving cylinder for driving the lifting column to lift, the lifting column is installed in the rotating frame and the top end of the lifting column extends out of the top end of the rotating frame to install a conductive cross arm.

7. An electric arc furnace with reliably drivable furnace covers according to claim 6, characterized in that A column guide structure is arranged in the rotating frame to prevent the lifting column from swinging when lifting.

8. The electric arc furnace with reliably drivable furnace covers as claimed in claim 1, characterized in that Further comprising a small furnace cover, the small furnace cover is provided with an electrode hole; an annular sealing wall is upwardly protruded on the large furnace cover, an annular slot is arranged in the small furnace cover, the annular slot is recessed upwardly from the bottom surface of the small furnace cover, the annular sealing wall is inserted into the annular slot, the slot width of the annular slot is greater than the thickness of the annular sealing wall, and the difference between them is designed so that the annular sealing wall does not interfere with the small furnace cover when the large furnace cover tilts.

9. An electric arc furnace with reliably drivable furnace covers according to claim 8, characterized in that The slot depth of the annular slot is not less than the height of the annular sealing wall.

10. The electric arc furnace with reliably drivable furnace covers as claimed in claim 8, characterized in that The annular sealing wall is an elliptical annular wall, the annular slot is an elliptical annular slot, and the long axis direction of both is parallel to the front-to-back line direction of the furnace.

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