Automatic opening and closing type access door for submerged arc furnace

Abstract

The utility model relates to an automatic opening and closing type access door for a submerged arc furnace, which comprises a door plate, a rotating shaft for the door plate to rotate and a mounting plate for the rotating shaft to be mounted, a rotating arm is arranged on one surface, deviating from the interior of a furnace body, of the door plate, and the rotating shaft is connected with the door plate through a pin shaft; the other end of the pin shaft penetrates through the rotating arm and is slidably connected with the rotating arm, the end, away from the door plate, of the pin shaft is in threaded connection with a fixing nut, and a moving space is formed between the fixing nut and the rotating arm. The rotating arm is fixedly connected with the rotating shaft, the mounting plate is fixedly mounted on the outer wall of the furnace body, and the rotating shaft is rotationally connected with the mounting plate through a bearing; a pneumatic motor is arranged on the mounting plate, and the output end of the pneumatic motor is connected with the rotating shaft through a speed reducer; the door plate is provided with a locking assembly used for locking the door plate. And a damper for enabling the door plate to rotate stably is arranged on the rotating arm. The access door has the effect of improving the opening and closing automation and safety of the access door.

Description

Technical Field

[0001] The utility model relates to the field of inspection doors, in particular to an automatic opening and closing inspection door for a submerged arc furnace. Background Art

[0002] The ore-reducing furnace, also known as the electric arc furnace, is mainly used for reducing and smelting ores. An inspection port is provided on the side wall of the ore-reducing furnace, and an inspection door is provided at the inspection port. After opening the inspection door, the staff can enter the furnace to inspect the furnace body.

[0003] Traditionally, the inspection door needs to be opened manually. However, harmful gases such as CO and NO are produced in the process of smelting ore. When the staff opens the inspection door, they come into close contact with the furnace body. The harmful gases in the furnace will float out through the door slot at the inspection door and cause harm to the human body. Therefore, a maintenance door that reduces safety hazards is needed. Utility Model Content

[0004] In order to solve the above technical problems, the present application provides an automatic opening and closing inspection door for an electric arc furnace.

[0005] The automatic opening and closing inspection door for the submerged arc furnace provided in this application adopts the following technical solution:

[0006] An automatic opening and closing inspection door for a submerged arc furnace comprises a door panel, a rotating shaft for rotating the door panel, and a mounting plate for mounting the rotating shaft. A rotating arm is arranged on the side of the door panel facing away from the inside of the furnace body, the rotating shaft is connected to the door panel through a pin shaft, one end of the pin shaft is fixedly connected to the door panel, the other end of the pin shaft passes through the rotating arm and is slidably connected to the rotating arm, a fixing nut is threadedly connected to the end of the pin shaft away from the door panel, a movable space is provided between the fixing nut and the rotating arm, the rotating arm is fixedly connected to the rotating shaft, the mounting plate is fixedly mounted on the outer wall of the furnace body, and the rotating shaft is rotatably connected to the mounting plate through a bearing;

[0007] The mounting plate is provided with a pneumatic motor, and the output end of the pneumatic motor is connected to the rotating shaft through a reducer;

[0008] The door panel is provided with a locking assembly for locking the door panel;

[0009] The rotating arm is provided with a damper for ensuring stable rotation of the door panel.

[0010] Preferably, the locking components are symmetrically arranged on the opposite side walls of the door panel, and each group of the locking components includes a locking plate and a locked shaft. The locking plate is rotatably arranged on the door panel, and the locked shaft is fixedly arranged on the outer wall of the furnace body through a connecting plate. A locking groove for the locked shaft to penetrate is provided on the locking plate, and the locking groove is arc-shaped. The cross-section of the locked shaft is semicircular, and the locking plate is rotated until the locked shaft penetrates into the locking groove or the locked shaft is disengaged from the locking groove.

[0011] Preferably, each group of the locking components is provided with two locking plates and two locked shafts, the two locking plates in the same group are connected by a connecting shaft, the connecting shaft is rotatably connected to the side wall of the door panel through a fixed plate, the fixed plate is fixedly connected to the door panel, and the connecting shaft is rotatably connected to the fixed plate.

[0012] Preferably, the locking components are arranged in two groups along the transverse direction and the longitudinal direction of the door panel.

[0013] Preferably, a driving cylinder is provided on the door panel, and a cylinder body of the driving cylinder is rotatably connected to the door panel via a connecting frame; a driving plate is fixedly connected to the connecting shaft, and a piston rod of the driving cylinder is rotatably connected to an end of the driving plate away from the connecting shaft via a connecting frame;

[0014] When the piston rod of the driving cylinder is not extended, the locked shaft is located outside the locking groove; after the piston rod of the driving cylinder is extended, the locked shaft penetrates into the locking groove of the locking plate.

[0015] Preferably, the two connecting shafts located on opposite sides of the door panel in the transverse direction are connected by a transverse connecting rod, and the two connecting shafts located on opposite sides of the door panel in the longitudinal direction are connected by a longitudinal connecting rod;

[0016] The two connecting shafts located on opposite sides of the door panel are driven to rotate by one of the driving cylinders, and the driving plate is connected to any one of the two connecting shafts on opposite sides of the door panel;

[0017] The two ends of the transverse connecting rod in the length direction are rotatably connected with transverse connecting plates, and one end of the transverse connecting plate away from the transverse connecting rod is fixedly connected to the corresponding connecting shaft, and the movement process of the transverse connecting plate is consistent with the movement process of the driving plate on the corresponding connecting shaft;

[0018] The two ends of the longitudinal connecting rod in the length direction are rotatably connected with longitudinal connecting plates, and one end of the longitudinal connecting plate away from the longitudinal connecting rod is fixedly connected to the corresponding connecting shaft, and the movement process of the longitudinal connecting plate is consistent with the movement process of the driving plate on the corresponding connecting shaft.

[0019] Preferably, the transverse connecting rod comprises two unit rod bodies and an auxiliary frame body, the auxiliary frame body is connected between the two unit rod bodies, the ends of the unit rod bodies away from each other are connected to corresponding transverse connecting plates, and the longitudinal connecting rod passes through the auxiliary frame body and can move inside the auxiliary frame body.

[0020] Preferably, the damper includes an outer cylinder and an inner rod, the outer cylinder is fixedly connected to the rotating arm through an auxiliary plate, the inner rod is slidably connected to the outer cylinder, a rubber spring is sleeved on the inner rod, and a bottom plate and a cover plate are respectively provided at two axial ends of the rubber spring, the bottom plate abuts against one end of the rubber spring close to the door panel, the cover plate abuts against one end of the rubber spring away from the bottom plate, the bottom plate is fixedly connected to the outer cylinder, the cover plate is slidably connected to the outer cylinder and the inner rod, a locking nut is threadedly connected to one end of the inner rod away from the door panel, and the locking nut abuts against one end of the cover plate away from the rubber spring.

[0021] Preferably, two rotating arms are arranged along the axial direction of the rotating shaft, and two dampers are arranged on each rotating arm.

[0022] Preferably, a sealing ring is provided on a surface of the door panel facing the furnace body, the sealing ring is provided along the peripheral side of the door panel, and the outer peripheral wall of the sealing ring is interference fit with the inner peripheral wall of the inspection port of the furnace body.

[0023] In summary, the present application includes at least one of the following beneficial technical effects:

[0024] 1. When the inspection door needs to be opened, the piston rod of the driving cylinder is controlled to retract, so that the locking plate is rotated until the locked shaft is out of the locking groove, and then the rotating shaft is driven to rotate by the pneumatic motor. The rotating shaft drives the door plate to rotate toward the outside of the furnace body through the rotating arm, thereby automatically opening the inspection door. When there are no staff, the harmful gas is discharged first. After the harmful gas is discharged for a period of time, the staff will go into the furnace for inspection, which not only saves time and effort, but also reduces the harm to the staff and ensures the safety of the staff;

[0025] 2. Through the setting of the locking assembly, when the inspection door does not need to be opened, the locked shaft is stably located in the locking groove of the locking plate, so that the door panel remains stably closed;

[0026] 3. Set up a damper to improve the stability of the door panel when it rotates;

[0027] 4. The setting of the sealing ring improves the sealing performance when the door panel is kept tightly closed between the furnace body inspection port. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the overall structure of the side of the automatic opening and closing inspection door for the ore-fired furnace facing away from the furnace body in the embodiment of the present application.

[0029] Figure 2 It is a structural schematic diagram used to illustrate the locking assembly in the embodiment of the present application.

[0030] Figure 3 It is a structural schematic diagram used to illustrate the connection relationship between the damper, the rotating arm and the door panel in the embodiment of the present application.

[0031] Figure 4 It is a schematic diagram of the structure of the sealing ring used to illustrate the embodiment of the present application.

[0032] Explanation of the reference numerals: 1. door panel; 11. rotating shaft; 111. bearing; 12. sealing ring; 2. mounting plate; 3. rotating arm; 31. pin shaft; 32. fixing nut; 4. pneumatic motor; 41. reducer; 5. locking assembly; 51. locking plate; 511. locking groove; 52. locked shaft; 521. connecting plate; 53. connecting shaft; 531. fixing plate; 6. driving cylinder; 61. connecting frame; 62. driving plate; 63. connecting frame; 7. horizontal connecting rod; 71. horizontal connecting plate; 72. unit rod body; 73. auxiliary frame body; 8. longitudinal connecting rod; 81. longitudinal connecting plate; 9. damper; 91. outer cylinder; 911. auxiliary plate; 92. inner rod; 921. locking nut; 93. rubber spring; 94. bottom plate; 95. cover plate. DETAILED DESCRIPTION

[0033] The following is combined with Figure 1-4 This application is described in further detail.

[0034] The embodiment of the present application discloses an automatic opening and closing inspection door for a submerged arc furnace.

[0035] Reference Figure 1-4 The automatic opening and closing inspection door for the electric arc furnace includes a door panel 1, a rotating shaft 11 for rotating the door panel 1, and a mounting plate 2 for installing the rotating shaft 11. A rotating arm 3 is arranged on the side of the door panel 1 facing away from the inside of the furnace body. The rotating shaft 3 is connected to the door panel 1 through a pin shaft 31. One end of the pin shaft 31 is fixedly connected to the door panel 1, and the other end of the pin shaft 31 passes through the rotating arm 3 and is slidably connected to the rotating arm 3. A fixing nut 32 is threadedly connected to the end of the pin shaft 31 away from the door panel 1, and there is a movable space between the fixing nut 32 and the rotating arm 3. In this embodiment, the movable space is 5 mm.

[0036] One end of the rotating arm 3 away from the door panel 1 is fixedly connected to the rotating shaft 11, the mounting plate 2 is fixedly mounted on the outer wall of the furnace body, and the rotating shaft 11 is rotatably connected to the mounting plate 2 via a bearing 111. An air motor 4 is arranged on the mounting plate 2, and the output end of the air motor 4 is connected to the rotating shaft 11 via a reducer 41. The furnace body is not shown in this embodiment.

[0037] The door panel 1 is provided with a locking assembly 5 for locking the door panel 1. The locking assembly 5 is symmetrically arranged at opposite side walls of the door panel 1, and each group of the locking assembly 5 includes a locking plate 51 and a locked shaft 52. The locking plate 51 is rotatably arranged on the door panel 1, and the locked shaft 52 is fixedly connected to the outer wall of the furnace body through a connecting plate 521. The locking plate 51 is provided with a locking groove 511 for the locked shaft 52 to penetrate. The locking groove 511 is arc-shaped, so that the locking plate 51 is hook-shaped as a whole, and the cross section of the locked shaft 52 is semicircular. The locking plate 51 is rotated until the locked shaft 52 penetrates into the locking groove 511 or the locked shaft 52 is separated from the locking groove 511.

[0038] Each locking assembly 5 is provided with two locking plates 51 and two locked shafts 52. The two locking plates 51 in the same group are connected by a connecting shaft 53. The connecting shaft 53 is rotatably connected to the side wall of the door panel 1 through a fixing plate 531. The fixing plate 531 is fixedly connected to the door panel 1, and the connecting shaft 53 is rotatably connected to the fixing plate 531.

[0039] The locking components 5 are arranged in two groups along the transverse direction of the door panel 1 and in the longitudinal direction of the door panel 1 .

[0040] The door panel 1 is provided with a driving cylinder 6, and the cylinder body of the driving cylinder 6 is rotatably connected to the door panel 1 through a connecting frame 61. A driving plate 62 is fixedly connected to the connecting shaft 53, and the piston rod of the driving cylinder 6 is rotatably connected to one end of the driving plate 62 away from the connecting shaft 53 through the connecting frame 63. The two connecting shafts 53 located on opposite sides of the door panel 1 are driven to rotate by one driving cylinder 6, and the driving plate 62 is connected to any one of the two connecting shafts 53 on opposite sides of the door panel 1.

[0041] When the piston rod of the driving cylinder 6 is not extended, the locked shaft 52 is located outside the locking groove 511; after the piston rod of the driving cylinder 6 is extended, the end of the driving plate 62 connected to the driving cylinder 6 rotates to the left or downward, driving the corresponding connecting shaft 53 to rotate, driving the locking plate 51 to rotate, and allowing the locked shaft 52 to penetrate into the locking groove 511 of the locking plate 51.

[0042] The two connecting shafts 53 located on opposite sides of the door panel 1 in the transverse direction are connected by a transverse connecting rod 7 , and the two connecting shafts 53 located on opposite sides of the door panel 1 in the longitudinal direction are connected by a longitudinal connecting rod 8 .

[0043] The two ends of the horizontal connecting rod 7 in the length direction are rotatably connected with the horizontal connecting plate 71, and the end of the horizontal connecting plate 71 away from the horizontal connecting rod 7 is fixedly connected to the corresponding connecting shaft 53, and the movement process of the horizontal connecting plate 71 is consistent with the movement process of the driving plate 62 on the corresponding connecting shaft 53. The two ends of the longitudinal connecting rod 8 in the length direction are rotatably connected with the longitudinal connecting plate 81, and the end of the longitudinal connecting plate 81 away from the longitudinal connecting rod 8 is fixedly connected to the corresponding connecting shaft 53, and the movement process of the longitudinal connecting plate 81 is consistent with the movement process of the driving plate 62 on the corresponding connecting shaft 53.

[0044] The transverse connecting rod 7 includes two unit rod bodies 72 and an auxiliary frame body 73. The auxiliary frame body 73 is connected between the two unit rod bodies 72. The ends of the unit rod bodies 72 that are away from each other are connected to the corresponding transverse connecting plate 71. The longitudinal connecting rod 8 passes through the auxiliary frame body 73 and can move in the auxiliary frame body 73.

[0045] In this embodiment, the two driving cylinders 6 are respectively located at the left connecting shaft 53 of the two connecting shafts 53 on the opposite sides of the door panel 1 in the horizontal direction and at the upper connecting shaft 53 of the two connecting shafts 53 on the opposite sides of the door panel 1 in the longitudinal direction.

[0046] When the driving cylinder 6 drives the left connecting shaft 53 to rotate, the left connecting shaft 53 drives the right connecting shaft 53 to move synchronously through the transverse connecting plate 71 and the transverse connecting rod 7. When the driving cylinder 6 drives the upper connecting shaft 53 to rotate, the upper connecting shaft 53 drives the lower connecting shaft 53 to move synchronously through the longitudinal connecting plate 81 and the longitudinal connecting rod 8, thereby realizing that one driving cylinder 6 controls the locked shafts 52 on both sides of the door panel 1 to be locked or unlocked synchronously.

[0047] By setting the locking assembly 5, when the inspection door does not need to be opened, the locked shaft 52 is stably located in the locking groove 511 of the locking plate 51, so that the door panel 1 is stably kept in a closed state.

[0048] The rotating arm 3 is provided with a damper 9 for making the door panel 1 rotate stably. The damper 9 includes an outer cylinder 91 and an inner rod 92. The outer cylinder 91 is fixedly connected to the rotating arm 3 through an auxiliary plate 911. The inner rod 92 is slidably connected to the outer cylinder 91. A rubber spring 93 is sleeved on the inner rod 92. The two axial ends of the rubber spring 93 are respectively provided with a bottom plate 94 and a cover plate 95. The bottom plate 94 abuts against the end of the rubber spring 93 close to the door panel 1. The cover plate 95 abuts against the end of the rubber spring 93 away from the bottom plate 94. The bottom plate 94 is fixedly connected to the outer cylinder 91. The cover plate 95 is slidably connected to the outer cylinder 91 and the inner rod 92. The end of the inner rod 92 away from the door panel 1 is threadedly connected with a locking nut 921. The locking nut 921 abuts against the end of the cover plate 95 away from the rubber spring 93. Two rotating arms 3 are provided along the axial direction of the rotating shaft 11, and two dampers 9 are provided on each rotating arm 3.

[0049] When the door panel 1 rotates, the rotating arm 3 compresses the rubber spring 93 through the bottom plate 94 and the cover plate 95 of the damper 9, so that the rotating arm 3 drives the door panel 1 to rotate slowly. During this process, movement occurs between the pin shaft 31 and the rotating arm 3, thereby improving the stability of the door panel 11 when rotating.

[0050] A sealing ring 12 is provided on the side of the door panel 1 facing the furnace body. The sealing ring 12 is arranged along the peripheral side of the door panel 1. The outer peripheral wall of the sealing ring 12 is interference fit with the inner peripheral wall of the inspection port of the furnace body, thereby improving the sealing performance of the door panel 1 when it is kept tightly closed between the inspection port of the furnace body.

[0051] The implementation principle of the automatic opening and closing inspection door for the submerged arc furnace in the embodiment of the present application is:

[0052] When it is necessary to open the inspection door, the piston rod of the control driving cylinder 6 is retracted, so that the locking plate 51 is rotated until the locked shaft 52 is disengaged from the locking groove 511, and then the rotating shaft 11 is driven to rotate by the pneumatic motor 4. The rotating shaft 11 drives the door panel 1 to rotate toward the outside of the furnace body through the rotating arm 3, thereby automatically opening the inspection door. When there are no staff, the harmful gas is discharged first. After the harmful gas has been discharged for a period of time, the staff can go into the furnace for maintenance. This not only saves time and effort, but also reduces the harm to the staff and ensures the safety of the staff.

[0053] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. An automatic opening and closing inspection door for a submerged arc furnace, characterized in that: The invention comprises a door panel (1), a rotating shaft (11) for rotating the door panel (1), and a mounting plate (2) for mounting the rotating shaft (11); a rotating arm (3) is arranged on a surface of the door panel (1) facing away from the interior of the furnace body; the rotating shaft is connected to the door panel (1) via a pin shaft (31); one end of the pin shaft (31) is fixedly connected to the door panel (1); the other end of the pin shaft (31) passes through the rotating arm (3) and is slidably connected to the rotating arm (3); a fixing nut (32) is threadedly connected to the end of the pin shaft (31) away from the door panel (1); and a movable space is provided between the fixing nut (32) and the rotating arm (3); the rotating arm (3) is fixedly connected to the rotating shaft (11); the mounting plate (2) is fixedly mounted on the outer wall of the furnace body; and the rotating shaft (11) is rotatably connected to the mounting plate (2) via a bearing (111); The mounting plate (2) is provided with a pneumatic motor (4), and the output end of the pneumatic motor (4) is connected to the rotating shaft (11) via a reducer (41); The door panel (1) is provided with a locking assembly (5) for locking the door panel (1); The rotating arm (3) is provided with a damper (9) for ensuring stable rotation of the door panel (1).

2. The automatic opening and closing inspection door for a submerged arc furnace according to claim 1 is characterized in that: The locking components (5) are symmetrically arranged at the opposite side walls of the door panel (1), and each group of the locking components (5) comprises a locking plate (51) and a locked shaft (52). The locking plate (51) is rotatably arranged on the door panel (1), and the locked shaft (52) is fixedly arranged on the outer wall of the furnace body through a connecting plate (521). The locking plate (51) is provided with a locking groove (511) for the locked shaft (52) to penetrate, and the locking groove (511) is arc-shaped. The cross section of the locked shaft (52) is semicircular. The locking plate (51) is rotated until the locked shaft (52) penetrates into the locking groove (511) or the locked shaft (52) is separated from the locking groove (511).

3. The automatic opening and closing inspection door for a submerged arc furnace according to claim 2 is characterized in that: Each group of the locking components (5) is provided with two locking plates (51) and two locked shafts (52); the two locking plates (51) in the same group are connected via a connecting shaft (53); the connecting shaft (53) is rotatably connected to the side wall of the door panel (1) via a fixing plate (531); the fixing plate (531) is fixedly connected to the door panel (1); and the connecting shaft (53) is rotatably connected to the fixing plate (531).

4. The automatic opening and closing inspection door for a submerged arc furnace according to claim 2 is characterized in that: The locking components (5) are arranged in two groups along the transverse direction of the door panel (1) and in the longitudinal direction of the door panel (1).

5. The automatic opening and closing inspection door for a submerged arc furnace according to claim 3 is characterized in that: The door panel (1) is provided with a driving cylinder (6), and the cylinder body of the driving cylinder (6) is rotatably connected to the door panel (1) via a connecting frame (61); a driving plate (62) is fixedly connected to the connecting shaft (53), and a piston rod of the driving cylinder (6) is rotatably connected to an end of the driving plate (62) away from the connecting shaft (53) via a connecting frame (63); When the piston rod of the driving cylinder (6) is not extended, the locked shaft (52) is located outside the locking groove (511); after the piston rod of the driving cylinder (6) is extended, the locked shaft (52) penetrates into the locking groove (511) of the locking plate (51).

6. The automatic opening and closing inspection door for a submerged arc furnace according to claim 5 is characterized in that: Two connecting shafts (53) located on opposite sides of the door panel (1) in the transverse direction are connected via a transverse connecting rod (7), and two connecting shafts (53) located on opposite sides of the door panel (1) in the longitudinal direction are connected via a longitudinal connecting rod (8); The two connecting shafts (53) located on opposite sides of the door panel (1) are driven to rotate by a driving cylinder (6), and the driving plate (62) is connected to any one of the two connecting shafts (53) located on opposite sides of the door panel (1); Both ends of the transverse connecting rod (7) in the length direction are rotatably connected with transverse connecting plates (71); one end of the transverse connecting plate (71) away from the transverse connecting rod (7) is fixedly connected to the corresponding connecting shaft (53); the movement process of the transverse connecting plate (71) is consistent with the movement process of the driving plate (62) on the corresponding connecting shaft (53); The two ends of the longitudinal connecting rod (8) in the length direction are rotatably connected to longitudinal connecting plates (81), and one end of the longitudinal connecting plate (81) away from the longitudinal connecting rod (8) is fixedly connected to the corresponding connecting shaft (53), and the movement process of the longitudinal connecting plate (81) is consistent with the movement process of the driving plate (62) on the corresponding connecting shaft (53).

7. The automatic opening and closing inspection door for a submerged arc furnace according to claim 6 is characterized in that: The transverse connecting rod (7) comprises two unit rod bodies (72) and an auxiliary frame body (73); the auxiliary frame body (73) is connected between the two unit rod bodies (72); one end of the unit rod bodies (72) away from each other is connected to a corresponding transverse connecting plate (71); and the longitudinal connecting rod (8) passes through the auxiliary frame body (73) and is movable in the auxiliary frame body (73).

8. The automatic opening and closing inspection door for a submerged arc furnace according to claim 1 is characterized in that: The damper (9) comprises an outer tube (91) and an inner rod (92); the outer tube (91) is fixedly connected to the rotating arm (3) through an auxiliary plate (911); the inner rod (92) is slidably connected to the outer tube (91); a rubber spring (93) is sleeved on the inner rod (92); two axial ends of the rubber spring (93) are respectively provided with a bottom plate (94) and a cover plate (95); the bottom plate (94) abuts against the rubber spring (93) near the door panel. The cover plate (95) is in contact with one end of the rubber spring (93) which is away from the bottom plate (94); the bottom plate (94) is fixedly connected to the outer tube (91); the cover plate (95) is slidably connected to the outer tube (91) and the inner rod (92); one end of the inner rod (92) which is away from the door panel (1) is threadedly connected with a locking nut (921); the locking nut (921) is tightly pressed against one end of the cover plate (95) which is away from the rubber spring (93).

9. The automatic opening and closing inspection door for a submerged arc furnace according to claim 8, characterized in that: Two rotating arms (3) are arranged along the axial direction of the rotating shaft (11), and two dampers (9) are arranged on each rotating arm (3).

10. The automatic opening and closing inspection door for a submerged arc furnace according to claim 1, characterized in that: A sealing ring (12) is provided on the side of the door panel (1) facing the furnace body. The sealing ring (12) is provided along the peripheral side of the door panel (1), and the outer peripheral wall of the sealing ring (12) is interference-fitted with the inner peripheral wall of the inspection opening of the furnace body.

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