A vacuum melting furnace

Abstract

The invention discloses a vacuum melting furnace, belonging to the technical field of melting devices. By arranging a material discharge part outside the furnace body, the structure inside the furnace body is simplified. When the furnace body is in a melting state, there are only a heating coil and a crucible. And by arranging the material discharge part outside the furnace body, after the melting is completed and the furnace body is opened, the first hydraulic cylinder is directly moved upward, and the round seat pushes away the support block. Under the joint resistance of the crucible and the round seat, the support block gives way, and the crucible is brought out with the downward movement of the round seat, and finally moves to the outside of the furnace body. At this time, an empty crucible can be placed in the heating coil, and the next metal melting can be directly carried out. The crucible with the molten metal brought out is outside the furnace body, and can be dumped in the next melting process. By externally placing the material discharge part and the replaceable crucible structure, the efficiency of metal melting is further improved, and the cleaning of the crucible after melting is also convenient, which has good economy.

Description

Technical Field

[0001] The invention belongs to the technical field of smelting devices, and in particular relates to a vacuum smelting furnace. Background Art

[0002] With the rapid development of modern industry, vacuum melting technology plays an increasingly important role in the field of metal material preparation. Traditional vacuum melting furnaces usually adopt an integrated design of furnace body, dumping device and crucible. Although it meets the production needs to a certain extent, this design has many shortcomings.

[0003] First, the integrated furnace body design makes the smelting furnace extremely inconvenient to maintain and clean. Once the crucible is damaged or needs to be replaced, the entire furnace body needs to stop working, which greatly increases production costs and time. Secondly, since the crucible is not replaceable, the service life of the furnace body is limited. Once the crucible is damaged, the efficiency and safety of the entire furnace body will be affected. In terms of technical research, although there have been some attempts to improve the existing smelting furnaces, most of the improvement measures have not fundamentally solved the problems of the irreplaceable crucible and the excessive size of the furnace body. Therefore, the present invention aims to propose a vacuum melting furnace with an external crucible replacement structure through innovative design, in order to solve the deficiencies in the prior art and meet the market demand for efficient and energy-saving melting furnaces. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a vacuum melting furnace, which can replace the crucible immediately and improve the melting efficiency of the furnace body.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention comprises a furnace body, a heating part, a crucible and a material discharge part arranged below the furnace body; the furnace body comprises a fixed half shell with a fixed position and a movable half shell that moves laterally, the heating part comprises a fixing frame fixed on the inner side of the fixed half shell and a vertical spiral heating ring arranged on the fixing frame, the crucible is a vertical cylindrical structure, a support plate is also extended laterally on the inner side of the fixed half shell, a through hole with an inner diameter larger than the outer diameter of the crucible is provided on the support plate, a plurality of support blocks supporting the bottom of the crucible are arranged on the inner side surrounding the through hole, and the support blocks and the support plate are connected to each other. The internal support is provided with a return spring, the lower side of the support block is an inclined surface, the unloading part includes a vertically arranged first hydraulic cylinder, the output end of the first hydraulic cylinder is arranged upward and connected to a round seat with the same diameter as the crucible, when the fixed half shell and the movable half shell are closed, the heating coil is located in the movable half shell, after the movable half shell is moved away, the heating coil is located above the unloading part, the first hydraulic cylinder moves the round seat upward, the round seat pushes against the support block and supports the crucible, and the first hydraulic cylinder moves the round seat downward, so that the crucible moves out of the heating coil with the round seat.

[0007] Furthermore, the unloading part also includes a baffle ring, a plurality of guide rods extend downward from the bottom end of the baffle ring, a plurality of connecting rods extend downward from the bottom surface of the round seat, the connecting rods are connected to a support ring, the guide rods are vertically slid on the support ring, a support spring is supported between the support ring and the baffle ring, and when the baffle ring is in a free state, the baffle ring is located on the outside of the round seat. During the unloading process, the first hydraulic cylinder moves the round seat upward, the baffle ring abuts against the bottom side of the support plate, and after the crucible moves downward with the round seat, the baffle ring is blocked on the outside of the crucible.

[0008] Furthermore, the unloading part also includes a base, the first hydraulic cylinder is rotatably arranged on the base, the first hydraulic cylinder is provided with a gear, the gear is coaxially arranged with the round seat, the base is also provided with a rack for transverse movement and an electric cylinder for driving the rack to move transversely, the rack is meshed with the gear, and a plurality of return grooves are provided around the edge of the round seat. When the first hydraulic cylinder drives the round seat carrying the crucible to move upward, the electric cylinder drives the round seat to rotate, so that the give way grooves correspond one by one to directly below the support block, the support block gives way under the resistance of the crucible, and returns to its position under the give way of the return grooves, so that the support block supports the crucible.

[0009] Furthermore, it also includes a sliding track arranged under the furnace body, and the unloading part also includes a moving seat, which is slidably arranged on the sliding track, and the edge of the base is hinged to the moving seat. A dumping device is also provided at the end of the sliding track, and the dumping device includes two fixed seats located on both sides of the sliding track, and a swing arm selected by a motor drive is provided on the fixed seat. When the unloading part moves to the end of the sliding track, the rotating shaft of the swing arm is coaxially arranged with the hinge axis of the base, and a second hydraulic cylinder is provided at the free end of the swing arm, and a clamping block clamped on the outside of the crucible is provided at the end of the second hydraulic cylinder. The second hydraulic cylinders on both sides drive the clamping blocks to clamp the crucible, and the swing arm drives the crucible to perform a dumping action.

[0010] Furthermore, an annular groove is provided on the outer side of the crucible, the clamping block is in an arc shape, and a step matching the annular groove is provided on the inner side of the clamping block.

[0011] Furthermore, there are two material discharge parts, which are connected side by side, and the two material discharge parts are slidably arranged on the sliding track, and a dumping device is respectively provided at both ends of the sliding track.

[0012] Furthermore, the fixing frame includes two vertical plates, the upper and lower ends of the two vertical plates are connected by a chain, one of the vertical plates is connected to a cross bar, the cross bar is fixed to the inner side of the fixed half shell, the heating coil is located between the two vertical plates, the inner side of the vertical plate is provided with a plurality of protrusions, the protrusions are supported between the gaps of the spiral heating coil

[0013] The beneficial effects of the present invention are:

[0014] The present invention simplifies the structure in the furnace body by arranging the material discharge part outside the furnace body. When the furnace body is in a smelting state, there are only heating coils and crucibles. Compared with the existing structure for directly arranging a structure for pouring molten metal in the furnace body, the volume of the furnace body is further reduced, which is conducive to the concentration of heat in the furnace body, improves the heating efficiency of the furnace body, and reduces the heating consumption in the furnace body. In addition, by arranging the material discharge part outside the furnace body, after smelting is completed and the furnace body is opened, the first hydraulic cylinder is directly moved upward, and the round seat pushes the support block away. Under the joint resistance of the crucible and the round seat, the support block allows the support block to move upward. The crucible is brought out with the downward movement of the round seat and finally moves to the outside of the furnace body. At this time, an empty crucible can be placed in the heating circle and the next metal smelting can be carried out directly. The crucible with molten metal is outside the furnace body and can be dumped during the next smelting process. The external placement of the discharge part and the replaceable crucible structure can further improve the efficiency of metal smelting, facilitate the cleaning of the crucible after smelting, and avoid occupying the furnace body space for cleaning the crucible after smelting. This device greatly improves the metal smelting efficiency of a smelting furnace and has good economy.

[0015] Other advantages, objectives and features of the present invention will be described in the following description and will be apparent to those skilled in the art to some extent, or those skilled in the art may be taught from the practice of the present invention. The objectives and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0017] Figure 1 This is an overall schematic diagram of a vacuum melting furnace according to an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of a blanking part and a heating part according to an embodiment of the present invention;

[0019] Figure 3 This is a cross-sectional view of the interior of a furnace body according to an embodiment of the present invention;

[0020] Figure 4 This is a schematic diagram of the working principle of the retaining ring according to an embodiment of the present invention;

[0021] Figure 5 This is a schematic diagram of the structure of a clamp block according to an embodiment of the present invention;

[0022] The markings in the accompanying drawings are as follows: 1. furnace body; 11. fixed half shell; 12. movable half shell; 2. heating part; 21. fixed frame; 211. vertical plate; 212. link; 213. cross bar; 22. heating coil; 3. crucible; 31. ring groove; 4. unloading part; 41. first hydraulic cylinder; 42. round seat; 421. connecting rod; 43. retaining ring; 431. guide rod; 432. supporting spring; 44. base; 441. gear; 442. rack; 443. electric cylinder; 45. moving seat; 5. support plate; 51. through hole; 52. support block; 53. return spring; 6. track; 7. tipping device; 71. fixed seat; 72. swing arm; 73. second hydraulic cylinder; 74. clamping block; 741. step. DETAILED DESCRIPTION

[0023] like Figures 1 to 5 As shown, the present invention discloses a vacuum melting furnace, comprising a furnace body 1, a heating part 2, a crucible 3 and a material discharge part 4 arranged below the furnace body 1; the furnace body 1 comprises a fixed half shell 11 with a fixed position and a movable half shell 12 that moves laterally, the fixed half shell 11 is fixed by a vertical support column and a fixed crossbeam, the movable half shell 12 is fixed on the vertical support column and a sliding beam that moves laterally on the top of the support column, the movable half shell 12 is driven to move by a hydraulic cylinder, and the fixed half shell 11 and the movable half shell 12 are sealed by magnetic attraction to achieve a good sealing state, and the sealing method is the existing technology and is not described in detail for the time being; reference Figure 2 and Figure 3 The heating part 2 includes a fixing frame 21 fixed to the inner side of the fixed half shell 11 and a vertical spiral heating coil 22 arranged on the fixing frame 21. The specific arrangement of the heating coil 22 is as follows: the fixing frame 21 includes two vertical plates 211, the upper and lower ends of the two vertical plates 211 are connected by a link 212, one of the vertical plates 211 is connected to a cross bar 213, and the cross bar 213 is fixed to the inner side of the fixed half shell 11. The heating coil 22 is located between the two vertical plates 211. The plate 211 is provided with a plurality of protrusions on the inner side, and the protrusions are supported between the gaps of the spiral heating coil 22. Through the setting of this frame, the heating coil 22 is fixed on the fixed frame 21 in a vertical spiral shape, and the spiral structure of the heating coil 22 is stable and does not deform through the vertical plate 211 and the protrusion structure; the crucible 3 is a vertical cylindrical structure, and the crucible 3 can slide vertically in the spiral heating coil 22; the inner side of the fixed half shell 11 is also horizontally extended with a support plate 5 for heating the metal inside the crucible 3 during smelting, refer to Figure 3 and Figure 4 The support plate 5 is provided with a through hole 51 whose inner diameter is larger than the outer diameter of the crucible 3. A plurality of support blocks 52 are arranged around the inner side of the through hole 51 to support the bottom of the crucible 3. The support blocks 52 and the support plate 5 are supported by return springs 53. The lower side of the support block 52 is an inclined surface. Figure 2The material discharging part 4 comprises a first hydraulic cylinder 41 which is vertically arranged. The output end of the first hydraulic cylinder 41 is arranged upward and connected with a round seat 42 which has the same diameter as the crucible 3. When the fixed half shell 11 and the movable half shell 12 are closed, the heating coil 22 is located in the movable half shell 12. After the movable half shell 12 is moved away, the heating coil 22 is located above the material discharging part 4. The first hydraulic cylinder 41 moves the round seat 42 upward, and the round seat 42 pushes away the supporting block 52 and supports the crucible 3. The first hydraulic cylinder 41 moves the round seat 42 downward, and the supporting block 52 is resisted by the crucible 3 and the outer side of the round seat 42, so that the crucible 3 can be moved out of the heating coil 22 along with the round seat 42.

[0024] This device simplifies the structure of the furnace body 1 by arranging the material discharge part 4 on the outside of the furnace body 1. When the furnace body 1 is in the smelting state, there are only the heating coil and the crucible 3. Compared with the existing furnace body 1 directly arranging the structure for pouring the molten metal, the volume of the furnace body 1 is further reduced, which is conducive to the concentration of heat in the furnace body 1, improves the heating efficiency of the furnace body 1, and reduces the heating consumption in the furnace body 1; and by arranging the material discharge part 4 on the outside of the furnace body 1, after the smelting is completed and the furnace body 1 is opened, the first hydraulic cylinder 41 is directly moved upward, and the round seat 42 pushes away the support block 52. Under the joint resistance of the crucible 3 and the round seat 42, the support block 52 is pushed away. The support block 52 gives way, and the crucible 3 is brought out with the downward movement of the round seat 42, and finally moves to the outside of the furnace body 1. At this time, the empty crucible 3 can be placed in the heating ring 22, and the next metal smelting can be carried out directly. The crucible 3 with molten metal brought out is outside the furnace body 1, and can be dumped during the next smelting process. The external placement of the discharge part 4 and the replaceable crucible 3 structure further improve the efficiency of metal smelting, and it is also convenient to clean the crucible 3 after smelting, so as to avoid the cleaning of the crucible 3 after smelting occupying the space of the furnace body 1. This device greatly improves the smelting efficiency of a smelting furnace for metal, and has good economic efficiency.

[0025] In a further solution, Figure 2 and Figure 3 As shown, the unloading portion 4 also includes a retaining ring 43, the inner diameter of the retaining ring 43 is slightly larger than the outer diameter of the crucible 3, and the height of the retaining ring 43 is smaller than the height of the crucible 3, a plurality of guide rods 431 extend downward from the bottom end of the retaining ring 43, a plurality of connecting rods 421 extend downward from the bottom surface of the round seat 42, the connecting rods 421 are connected with a supporting ring, the guide rods 431 are vertically slidably arranged on the supporting ring, a supporting spring 432 is supported between the supporting ring and the retaining ring 43, when the retaining ring 43 is in a free state, that is, under the support of the supporting spring 432, the bottom end of the retaining ring 43 is flush with the bottom end of the round seat 42, the top end of the retaining ring 43 is higher than the top end of the round seat 42, and the retaining ring 43 is located outside the round seat 42, with reference to Figure 3During the unloading process, the first hydraulic cylinder 41 moves the round seat 42 upward, and the retaining ring 43 abuts against the bottom side of the support plate 5. After the crucible 3 moves downward with the round seat 42, the retaining ring 43 is blocked on the outside of the crucible 3.

[0026] By setting up this structure, during the unloading process, as the round seat 42 descends, the retaining ring 43 is always placed on the outside of the crucible 3, which can protect and support the supported crucible 3 from the outside, prevent the crucible 3 from shifting on the round seat 42 and causing the crucible 3 to fall from the round seat 42, and ensure the safety of removing the crucible 3.

[0027] In a further solution, Figure 2 As shown, the unloading part 4 also includes a base 44, the first hydraulic cylinder 41 is rotatably arranged on the base 44, the first hydraulic cylinder 41 is provided with a gear 441, the gear 441 is coaxially arranged with the round seat 42, the base 44 is also provided with a rack 442 for transverse movement and an electric cylinder 443 for driving the rack 442 to move transversely, the rack 442 is meshed with the gear 441, and a plurality of return grooves are provided around the edge of the round seat 42, the number of the return grooves is the same as the number of the support blocks 52, when the first hydraulic cylinder 41 drives the round seat 42 carrying the crucible 3 to move upward, the electric cylinder 443 drives the round seat 42 to rotate, so that the make way grooves correspond one by one to directly below the support block 52, the support block 52 makes way under the resistance of the crucible 3, and returns to its place under the make way of the return grooves, so that the support block 52 supports the crucible 3.

[0028] This structure adds a loading structure for the crucible 3. After the giving way groove is set, the round seat 42 rotates at a certain angle under the drive of the electric cylinder 443. The rotation of the round seat 42 can change the resistance state of the round seat 42 to the support block 52. During the unloading process, the outer side of the round seat 42 resists the support block 52. With the support of the crucible 3, it can be ensured that the support block 52 is retracted to the inner side of the through hole 51, so that the crucible 3 is taken out with the round seat 42. When the crucible 3 is needed for assembly, the crucible 3 is placed on the round seat 42. As the round seat 42 rises and rotates, the returning groove gives way to the support block 52, so that the crucible 3 moves above the support block 52, and the support block 52 rebounds. The crucible 3 is supported by the support block 52 again. At this time, the round seat 42 is retracted, and the next smelting operation can be carried out. The newly added loading structure can improve the loading speed of the crucible 3, and there is no need to set other devices for clamping and placing the crucible 3 on the heating ring 22.

[0029] In a further solution, Figure 1As shown, it includes a sliding track 6 arranged below the furnace body 1, and the cross section of the sliding track 6 is a T-shaped structure. The unloading part 4 also includes a moving seat 45, and the moving seat 45 is slidably arranged on the sliding track 6. A pulley driven by a motor is arranged inside the moving seat 45, so that the moving seat 45 can be electrically driven to reciprocate on the sliding track 6. The edge of the base 44 is hinged to the moving seat 45, and a dumping device 7 is also provided at the end of the sliding track 6. The dumping device 7 includes two fixed seats 71 located on both sides of the sliding track 6, and a swing arm 72 driven by a motor is provided on the fixed seat 71. When the unloading part 4 moves to the end of the sliding track 6, the rotating shaft of the swing arm 72 is coaxially arranged with the hinge axis of the base 44, and a second hydraulic cylinder 73 is provided at the free end of the swing arm 72. The end of the second hydraulic cylinder 73 is provided with a clamping block 74 clamped on the outside of the crucible 3, as shown in FIG. Figure 4 and Figure 5 As shown, the outer side of the crucible 3 is provided with an annular groove 31, the clamping block 74 is in an arc shape, the inner side of the clamping block 74 is provided with a locking step 741 that cooperates with the annular groove 31, and the second hydraulic cylinders 73 on both sides drive the clamping block 74 to clamp the crucible 3. After clamping the crucible 3, the swing arm 72 drives the crucible 3 to tip over.

[0030] By setting a slide rail structure, the crucible 3 after unloading is moved out from the bottom side of the furnace body 1, which is convenient for pouring the molten metal in the crucible 3. The set dumping structure is used to clamp the crucible 3 with two clamping blocks 74 after the crucible 3 is moved out. With the rotation of the swing arm 72, the coaxially arranged base 44 rotates together, and the crucible 3 performs a dumping action, wherein the crucible 3 is provided with an annular groove 31, and the clamping block 74 is provided with a step 741, which can ensure that the crucible 3 will not fall during the dumping process. The dumping structure is arranged in conjunction with the unloading part 4, and the crucible 3 does not need to be removed from the crucible 3, and the metal can be quickly dumped. In addition, the crucible 3 has a large dumping angle, and the molten metal can be completely dumped, which is convenient for cleaning the crucible 3.

[0031] In a further solution, Figure 1 As shown, there are two material discharge parts 4, which are connected side by side. The two material discharge parts 4 are slidably arranged on the sliding track 6, and a dumping device 7 is respectively provided at both ends of the sliding track 6.

[0032] By arranging chain unloading parts 4 and two dumping devices 7, the continuous working efficiency of the device is further improved. During the unloading process, the metal in the crucible 3 can be placed for the next time. After the unloading is completed, the unloading part 4 is moved out of the furnace body 1, and the molten metal is dumped through the dumping device 7. By moving the unloading part 4, the other unloading part 4 is moved to the bottom of the furnace body 1. When the metal is dumped, the crucible 3 can be loaded, and this cycle is repeated. The device reduces the idle time of the furnace body 1 and improves the efficiency of metal smelting.

[0033] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A vacuum melting furnace, characterized in that: The invention comprises a furnace body (1), a heating part (2), a crucible (3), and a material discharge part (4) arranged below the furnace body (1); the furnace body (1) comprises a fixed half shell (11) and a movable half shell (12) which moves laterally; the heating part (2) comprises a fixing frame (21) fixed to the inner side of the fixed half shell (11) and a vertical spiral heating ring (22) arranged on the fixing frame (21); the crucible (3) is in the form of a vertical cylindrical structure; a support plate (5) is also arranged on the inner side of the fixed half shell (11) to extend laterally; a groove having an inner diameter larger than that of the crucible (3) is formed on the support plate (5); A through hole (51) with an outer diameter of 1.5 mm is formed, and a plurality of support blocks (52) are arranged on the inner side surrounding the through hole (51) for supporting the bottom of the crucible (3). The support blocks (52) and the support plate (5) are supported internally by return springs (53). The lower side of the support blocks (52) is an inclined surface. The unloading portion (4) comprises a first hydraulic cylinder (41) arranged vertically. The output end of the first hydraulic cylinder (41) is arranged upward and connected to a round seat (42) having the same diameter as the crucible (3). When the fixed half shell (11) and the movable half shell (12) are closed, the heating coil (22) is located inside the movable half shell (12). After the movable half shell (12) is moved away, the heating ring (22) is located above the unloading portion (4), the first hydraulic cylinder (41) moves the round seat (42) upward, the round seat (42) pushes away the supporting block (52) and supports the crucible (3), and the first hydraulic cylinder (41) moves the round seat (42) downward, so that the crucible (3) moves out of the heating ring (22) along with the round seat (42); the unloading portion (4) further comprises a retaining ring (43), a plurality of guide rods (431) extending downward from the bottom end of the retaining ring (43), and a plurality of guide rods (431) extending downward from the bottom surface of the round seat (42) A connecting rod (421), wherein the connecting rod (421) is connected to a support ring, the guide rod (431) is vertically slidably arranged on the support ring, a support spring (432) is supported between the support ring and the retaining ring (43), and when the retaining ring (43) is in a free state, the retaining ring (43) is located outside the round seat (42), and during the material unloading process, the first hydraulic cylinder (41) moves the round seat (42) upward, and the retaining ring (43) abuts against the bottom side of the support plate (5), and after the crucible (3) moves downward with the round seat (42), the retaining ring (43) is blocked outside the crucible (3);The unloading portion (4) further comprises a base (44), the first hydraulic cylinder (41) being rotatably disposed on the base (44), a gear (441) being disposed on the first hydraulic cylinder (41), the gear (441) being coaxially disposed with the round seat (42), the base (44) further comprising a rack (442) for transverse movement and an electric cylinder (443) for driving the rack (442) for transverse movement, the rack (442) being meshed with the gear (441) and surrounding the A plurality of return grooves are provided on the edge of the round seat (42). When the first hydraulic cylinder (41) drives the round seat (42) carrying the crucible (3) to move upward, the electric cylinder (443) drives the round seat (42) to rotate, so that the return grooves correspond one by one directly below the support block (52). The support block (52) returns to its original position under the resistance of the crucible (3) and returns to its original position under the return grooves, so that the support block (52) supports the crucible (3). The furnace body (1) is also provided below the furnace body (1). The material discharging part (4) further comprises a movable seat (45), the movable seat (45) being slidably arranged on the sliding track (6), the edge of the base (44) being hinged on the movable seat (45), and a dumping device (7) being further provided at the end of the sliding track (6), the dumping device (7) comprising two fixed seats (71) located on both sides of the sliding track (6), the fixed seats (71) being provided with a swing arm (72) driven and selected by a motor, and when the material discharging part (4) moves to the end of the sliding track (6), the rotating shaft of the swing arm (72) is coaxially arranged with the hinge shaft of the base (44), the free end of the swing arm (72) is provided with a second hydraulic cylinder (73), the end of the second hydraulic cylinder (73) is provided with a clamping block (74) clamped on the outside of the crucible (3), the second hydraulic cylinders (73) on both sides drive the clamping block (74) to clamp the crucible (3), and the swing arm (72) drives the crucible (3) to perform a dumping action. ; 2. The vacuum melting furnace according to claim 1, characterized in that: An annular groove (31) is provided on the outside of the crucible (3); the clamping block (74) is in an arc shape; and a clamping step (741) matching the annular groove (31) is provided on the inside of the clamping block (74).

3. The vacuum melting furnace according to claim 2, characterized in that: There are two material discharge parts (4), the two material discharge parts (4) are connected side by side, the two material discharge parts (4) are slidably arranged on the sliding track (6), and a dumping device (7) is respectively provided at both ends of the sliding track (6).

4. The vacuum melting furnace according to claim 1, characterized in that: The fixing frame (21) comprises two vertical plates (211), the upper and lower ends of the two vertical plates (211) are connected by a link (212), one of the vertical plates (211) is connected to a cross bar (213), the cross bar (213) is fixed to the inner side of the fixed half shell (11), the heating coil (22) is located between the two vertical plates (211), and a plurality of protrusions are provided on the inner side of the vertical plate (211), and the protrusions are supported between the gaps of the spiral heating coil (22).

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