Distillation device for translocation tetrahydroimine production and use method thereof

Abstract

The invention relates to the technical field of translocation tetrahydroimine production, in particular to a distillation device for translocation tetrahydroimine production and a use method of the distillation device. Comprising a cube-shaped kettle body, the upper end of the kettle body is detachably, fixedly and hermetically connected with a cover body, two opposite angles in the kettle body are fixedly connected through a sliding rail, the sliding rail is located in the upper end of the kettle body, a sliding block is slidably arranged in the sliding rail, rotating plates are rotatably and hermetically connected in the inner angles of the kettle body on the left side and the right side of the sliding rail, and the lower ends of the rotating plates are slidably and hermetically connected with the kettle bottom of the kettle body. Folding units are rotationally and hermetically connected to the free ends of the rotating plates, the lower ends of the folding units are in sliding and sealing contact with the kettle bottom of the kettle body, and the opposite ends of the two folding units are rotationally connected with the sliding blocks. The rotating plate and the folding unit can reduce the volume in the first cavity or the second cavity, so that the liquid level height of the liquid material in the first cavity or the second cavity can be guaranteed, and it is guaranteed that the liquid material in the first cavity or the second cavity can wrap the second heating plate.

Description

Technical Field

[0001] The invention relates to the technical field of metathesis tetrahydroimine production, and in particular to a distillation device for metathesis tetrahydroimine production and a use method thereof. Background Art

[0002] Transposition tetrahydrophthalimide is mainly used for the synthesis of new electronic materials and the synthesis of pesticide cypermethrin. The transposition tetrahydrophthalic anhydride is transferred to the transposition tetrahydrophthalic anhydride synthesis kettle and stirred. The jacket is heated to 130-135°C by steam. Urea is added to the synthesis kettle to carry out the synthesis reaction. After the synthesis reaction is completed, crude 3,4,5,6-tetrahydrophthalimide is obtained. After the synthesis reaction is completed, the jacket of the synthesis kettle is cooled to 50°C by water. Ethanol is added to the crude 3,4,5,6-tetrahydrophthalimide in the synthesis kettle to obtain a liquid material. The liquid material is then transferred to a distillation kettle and heated and concentrated for 0.5 hours. After heating and concentration, the material is discharged into a crystallization tank. The transposition tetrahydrophthalimide is obtained by cooling and crystallizing for 12 hours. After centrifugation and reduced pressure drying, it is packaged and stored.

[0003] When the liquid material is heated in the distillation kettle, the liquid level of the liquid material decreases as part of the ethanol evaporates. The heating body of some existing distillation kettles is vertically arranged in the distillation kettle. After the liquid level of the liquid material decreases, the part of the heating body exposed above the liquid material surface is prone to dry burning, thereby affecting the service life of the heating body. Therefore, it is necessary to provide a distillation device for producing transposition tetrahydroimine with a variable cavity so that the liquid material always wraps the heating body. Summary of the invention

[0004] The main purpose of the present invention is to provide a distillation device for producing transposition tetrahydroimine, which has a variable volume cavity and can ensure that liquid materials always wrap around a heating body, and a method for using the distillation device.

[0005] In order to achieve the above object, the technical solution provided by the present invention is: A distillation device for producing metathesis tetrahydroimine comprises a cubic kettle body, the upper end of the kettle body is detachably fixedly sealed and connected with a cover body, a row pipe is fixed on the cover body, the row pipe is communicated with the inside of the kettle body, two diagonal corners of the kettle body are fixedly connected by a slide rail, the slide rail is located in the upper end of the kettle body, a slider is slidably arranged in the slide rail, a rotating plate is rotatably sealed and connected in the inner corners of the kettle body on the left and right sides of the slide rail, the lower end of the rotating plate is slidably sealed and connected with the bottom of the kettle body, a folding unit is rotatably sealed and connected on the free end of the rotating plate, and the lower end of the folding unit is rotatably sealed and connected with the bottom of the kettle body The bottom is in sliding sealing contact, and the opposite ends of the two folding units are rotatably connected to the slider. The opposite ends of the two folding units are in rotating sealing contact. A second heating plate is fixed on the inner wall of the kettle body, and a motor is fixed on the cover body. The output shaft of the motor is fixedly connected to a rotating plate on one side of the motor, and the motor can drive the rotating plate to rotate in the kettle body; when the motor drives the rotating plate to rotate, the two folding units are folded and move toward the middle direction of the kettle body. After the folding units move toward the middle direction of the kettle body, the two rotating plates and the two folding units separate the inside of the kettle body into a first cavity and a second cavity.

[0006] Specifically, the folding unit includes a plurality of folding parts, and the folding parts include two baffles. The opposite ends of the two baffles are rotatably connected by a connecting plate, and the opposite ends of the two baffles are in rotational sealing contact. The lower end of the baffle is in sliding sealing contact with the bottom of the kettle body. The two baffles opposite to two adjacent folding parts are rotatably connected by a connecting block. The two baffles opposite to two adjacent folding parts are in rotational sealing contact. The rotating plate and its adjacent baffles are rotatably connected by a connecting block. The connecting block on one side of the rotating plate is fixedly connected to the rotating plate. The baffle adjacent to the rotating plate is elastically rotatably connected to the connecting block fixed on the rotating plate. The rotating plate and its adjacent baffles are in rotational sealing contact. The adjacent connecting blocks are connected by a spring rod, and the adjacent connecting blocks are respectively connected to the two ends of the spring rod. Fixed connection; the two adjacent baffles of the two folding units are rotatably connected through a connecting piece, the two adjacent baffles of the two folding units are rotatably sealed and contacted, the connecting piece is rotatably connected with a second connecting seat, the upper end of the second connecting seat is rotatably connected with the first connecting seat, the first connecting seat is rotatably connected to the slider, the connecting block adjacent to the first connecting seat in one folding unit and the first connecting seat are connected through a spring rod, the connecting block adjacent to the second connecting seat in the other folding unit and the second connecting seat are connected through a spring rod, both ends of the spring rod connecting the first connecting seat and the connecting block are fixedly connected to the first connecting seat and the connecting block respectively, and both ends of the spring rod connecting the second connecting seat and the connecting block are fixedly connected to the second connecting seat and the connecting block respectively.

[0007] Specifically, a third heating plate is fixed on each of the baffles.

[0008] Specifically, the rotating plates are all fixed with first heating plates.

[0009] Specifically, a first inlet pipe and a second inlet pipe respectively connected to the first cavity and the second cavity are fixed on the kettle body.

[0010] Specifically, the baffle plate adjacent to the rotating plate and the connecting block fixed on the rotating plate are connected via a torsion spring.

[0011] A method for using a distillation device for producing metathesis tetrahydroimine: before adding liquid material into a kettle, two rotating plates are in close contact with two adjacent inner walls of the kettle, and two folding units are in an extended state and in close contact with the inner wall of the kettle on one side, at which time a first cavity is compressed; liquid material is added into a second cavity in the kettle and a second heating plate in the second cavity is started; when the second heating plate in the second cavity heats the liquid material in the second cavity, volatile ethanol is discharged through a discharge pipe, and the liquid level of the liquid material in the second cavity is reduced; during the heating process, a motor is started so that the motor drives the rotating plate and the folding unit to move toward the middle of the kettle; when the rotating plate and the folding unit move toward the middle of the kettle, the folding unit folds, the volume of the second cavity is reduced, and the volume of the first cavity is gradually increased; during the process of reducing the volume of the second cavity, the liquid level of the liquid material in the second cavity can be maintained, thereby preventing the upper part of the second heating plate in the second cavity from being exposed above the liquid level of the liquid material and causing dry burning; after the liquid material in the second cavity is heated, the second heating plate in the second cavity is closed, and then the heated material in the second cavity is released and cooled for crystallization.

[0012] Then, liquid material is added into the first cavity and the second heating plate in the first cavity is started. When the second heating plate in the first cavity heats the liquid material in the first cavity, steam is discharged through the exhaust pipe, and the liquid level of the liquid material in the first cavity is lowered. During the heating process, the motor is started so that the motor drives the rotating plate and the folding unit to gradually restore. During the process of the motor driving the rotating plate and the folding unit to gradually restore, the volume of the first cavity gradually decreases. During the process of reducing the volume of the first cavity, the liquid level of the liquid material in the first cavity can be maintained, thereby avoiding the situation of dry burning due to the upper part of the second heating plate in the first cavity being exposed above the liquid level of the liquid material.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. In the process of heating the liquid material in the first cavity or the second cavity, the rotating plate and the folding unit can reduce the volume in the first cavity or the second cavity, thereby ensuring the liquid level of the liquid material in the first cavity or the second cavity, ensuring that the liquid material in the first cavity or the second cavity can wrap the second heating plate, avoiding the situation where the second heating plate is partially located above the liquid material and dry burning occurs, and can increase the service life of the second heating plate.

[0014] 2. By arranging the first heating plate and the third heating plate on the rotating plate and the baffle plate respectively, the heating efficiency of the liquid material can be improved.

[0015] 3. The folding unit can be folded or extended during the rotation of the rotating plate, which can effectively change the volume of the first cavity and the second cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the distillation apparatus.

[0017] Figure 2 Schematic diagram of the internal structure of the kettle.

[0018] Figure 3 A top view of the kettle body.

[0019] Figure 4 It is a top view when the volume of the second cavity is reduced.

[0020] Figure 5 This is a three-dimensional diagram when the volume of the second cavity is reduced.

[0021] Figure 6 It is a schematic diagram of the folding unit when it is folded.

[0022] Figure 7 for Figure 6 Magnified view of area A.

[0023] Figure 8 Schematic diagram of the connection between the slider and the connecting piece.

[0024] The names of the parts in the accompanying drawings are: 1. kettle body; 2. upper cover; 3. row pipe; 4. motor; 5. second inlet pipe; 6. rotating plate; 7. first heating plate; 8. baffle; 9. slide rail; 10. first inlet pipe; 11. connecting block; 12. slider; 13. first cavity; 14. second cavity; 15. connecting plate; 16. spring rod; 17. second heating plate; 18. connecting piece; 19. third heating plate; 20. first connecting seat; 21. second connecting seat. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0026] like Figure 1-Figure 8 As shown, a distillation device for producing metathesis tetrahydroimine comprises a cubic kettle body 1, the upper end of which is detachably fixedly and sealedly connected with a cover body 2, on which a discharge pipe 3 is fixed, and the discharge pipe 3 is connected with the interior of the kettle body 1.

[0027] The two diagonal corners in the kettle body 1 are fixedly connected by a slide rail 9, and the slide rail 9 is located in the upper end of the kettle body 1. A slider 12 is slidably arranged in the slide rail 9. The inner corners of the kettle body 1 on the left and right sides of the slide rail 9 are rotatably sealed with a rotating plate 6, and the first heating plate 7 is fixed on the rotating plate 6. The lower end of the rotating plate 6 is slidably sealed with the bottom of the kettle body 1, and the free end of the rotating plate 6 is rotatably sealed with a folding unit, and the lower end of the folding unit is in slidably sealed contact with the bottom of the kettle body 1, and the opposite ends of the two folding units are rotatably connected with the slider 12, and the opposite ends of the two folding units are in rotatably sealed contact.

[0028] A second heating plate 17 is fixed on the inner wall of the kettle body 1 .

[0029] A motor 4 is fixed on the cover body 2, and the output shaft of the motor 4 is fixedly connected to the rotating plate 6 on one side thereof, and the motor 4 can drive the rotating plate 6 to rotate in the kettle body 1. When the motor 4 drives the rotating plate 6 to rotate, both folding units are folded and move toward the middle direction of the kettle body 1. After the folding units move toward the middle direction of the kettle body 1, the two rotating plates 6 and the two folding units divide the inside of the kettle body 1 into a first cavity 13 and a second cavity 14.

[0030] The kettle body 1 is fixed with a first inlet pipe 10 and a second inlet pipe 5 which are connected with the first cavity 13 and the second cavity 14 respectively.

[0031] The folding unit includes a plurality of folding members.

[0032] The folding member includes two baffles 8, the opposite ends of the two baffles 8 are rotatably connected by a connecting plate 15, and the opposite ends of the two baffles 8 are rotatably sealed. The lower end of the baffle 8 is in sliding and sealing contact with the bottom of the kettle body 1. The baffles 8 are fixed with a third heating plate 19.

[0033] The two baffles 8 opposite to the two adjacent folding members are rotatably connected through the connecting block 11, and the two baffles 8 opposite to the two adjacent folding members are rotatably sealed and contacted.

[0034] The rotating plate 6 and the adjacent baffle plate 8 are rotatably connected via a connecting block 11. The connecting block 11 on one side of the rotating plate 6 is fixedly connected to the rotating plate 6. The baffle plate 8 adjacent to the rotating plate 6 is elastically rotatably connected to the connecting block 11 fixed on the rotating plate 6. Specifically, the baffle plate 8 adjacent to the rotating plate 6 and the connecting block 11 fixed on the rotating plate 6 are connected via a torsion spring. The rotating plate 6 and the adjacent baffle plate 8 are in rotatable sealing contact.

[0035] The two adjacent connection blocks 11 are connected by a spring rod 16 , and the two adjacent connection blocks 11 are fixedly connected to two ends of the spring rod 16 respectively.

[0036] The two adjacent baffles 8 of the two folding units are rotatably connected through the connecting piece 18, and the two adjacent baffles 8 of the two folding units are rotatably sealed and contacted.

[0037] The connecting piece 18 is rotatably connected to the second connecting seat 21, the upper end of the second connecting seat 21 is rotatably connected to the first connecting seat 20, and the first connecting seat 20 is rotatably connected to the slider 12. The connecting block 11 adjacent to the first connecting seat 20 in one folding unit is connected to the first connecting seat 20 through a spring rod 16, and the connecting block 11 adjacent to the second connecting seat 21 in another folding unit is connected to the second connecting seat 21 through a spring rod 16.

[0038] Specifically, the two ends of the spring rod 16 connecting the first connection seat 20 and the connection block 11 are respectively fixedly connected to the first connection seat 20 and the connection block 11. The two ends of the spring rod 16 connecting the second connection seat 21 and the connection block 11 are respectively fixedly connected to the second connection seat 21 and the connection block 11.

[0039] Transfer the metathesis tetrahydrophthalic anhydride to the synthesis kettle and start stirring. Pass steam into the jacket of the synthesis kettle to heat it to 130°C-135°C. Add urea into the synthesis kettle to carry out synthesis reaction.

[0040] After the synthesis reaction is completed, water is introduced into the jacket of the synthesis kettle to cool it down to 50°C, and ethanol is added to the synthesis kettle to form liquid material in the synthesis kettle. The liquid material is then transferred to the kettle body 1 of the distillation kettle.

[0041] Before adding liquid material into the kettle body 1 of the distillation kettle, the two rotating plates 6 are close to the two adjacent inner walls of the kettle body 1, and the two folding units are in an extended state and close to the inner wall of the kettle body 1 on one side. At this time, the first cavity 13 is compressed.

[0042] Liquid material is added into the second cavity 14 in the kettle body 1 through the second inlet pipe 5, and the second heating plate 17 in the second cavity 14, the first heating plate 7 on the rotating plate 6, and the three heating plates on the baffle 8 are started. The second heating plate 17, the third heating plate 19, and the first heating plate 7 in the second cavity 14 heat the liquid material in the second cavity 14 for 0.5 hours. During the heating process, the volatilized ethanol is discharged through the drain pipe 3, and the liquid level of the liquid material in the second cavity 14 is reduced.

[0043] During the heating process, the motor 4 is started, so that the motor 4 drives the rotating plate 6 and the folding unit to move toward the middle direction of the kettle body 1. When the rotating plate 6 and the folding unit move toward the middle direction of the kettle body 1, the baffle 8 rotates to fold, and the two adjacent connecting blocks 11 approach each other, the spring rod 16 contracts, and the slider 12 slides in the slide rail 9. The volume of the second cavity 14 decreases, and the volume of the first cavity 13 gradually increases. During the process of reducing the volume of the second cavity 14, the liquid level of the liquid material in the second cavity 14 can be maintained, thereby avoiding the second heating plate 17, the first heating plate 7 and the upper part of the third heating plate 19 in the second cavity 14 being exposed above the liquid surface of the liquid material and causing dry burning.

[0044] After the liquid material in the second cavity 14 is heated, the second heating plate 17 in the second cavity 14 is turned off, and then the liquid material in the second cavity 14 is discharged into the crystallization tank, cooled and crystallized for 12 hours to obtain trans-tetrahydroimine, which is packaged and stored after centrifugation and reduced pressure drying.

[0045] Then, liquid material is added into the first cavity 13 and the second heating plate 17 in the first cavity 13 is started, and the first heating plate 7 and the third heating plate 19 are kept turned on. The second heating plate 17, the first heating plate 7 and the third heating plate 19 in the first cavity 13 heat the liquid material in the first cavity 13 for 0.5 hours. During the heating process, the volatilized ethanol is discharged through the drain pipe 3, and the liquid level of the liquid material in the first cavity 13 is lowered. During the heating process, the motor 4 is started, so that the motor 4 drives the rotating plate 6 and the folding unit to gradually restore. During the gradual restoration of the rotating plate 6 and the folding unit, the spring rod 16 gradually extends, the baffle 8 rotates to restore, and the slider 12 slides in the slide rail 9 toward the end direction of one side thereof. As the motor 4 drives the rotating plate 6 and the folding unit to gradually restore, the volume of the first cavity 13 gradually decreases. During the reduction of the volume of the first cavity 13, the liquid level of the liquid material in the first cavity 13 can be maintained, thereby preventing the upper parts of the second heating plate 17, the first heating plate 7 and the third heating plate 19 in the first cavity 13 from being exposed above the liquid level of the liquid material and causing dry burning.

[0046] After the heating of the liquid material in the first cavity 13 is completed, the second heating plate 17 in the first cavity 13 is turned off, the first heating plate 7 and the third heating plate 19 are turned off, and then the liquid material in the first cavity 13 is discharged into the crystallization tank, cooled and crystallized for 12 hours to obtain trans-tetrahydroimine, which is packaged and stored after centrifugation and reduced pressure drying.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A distillation device for producing metathesis tetrahydroimine, comprising a cubic kettle (1), the upper end of which is detachably fixedly and sealedly connected with a cover (2), a row pipe (3) is fixed on the cover (2), and the row pipe (3) is connected to the interior of the kettle (1), characterized in that: Two diagonal corners in the kettle body (1) are fixedly connected by a slide rail (9), the slide rail (9) is located in the upper end of the kettle body (1), a slider (12) is slidably arranged in the slide rail (9), the inner corners of the kettle body (1) on the left and right sides of the slide rail (9) are both rotatably sealed and connected with a rotating plate (6), the lower end of the rotating plate (6) is slidably sealed and connected with the bottom of the kettle body (1), the free end of the rotating plate (6) is rotatably sealed and connected with a folding unit, the lower end of the folding unit is in slidably sealed contact with the bottom of the kettle body (1), the opposite ends of the two folding units are rotatably connected with the slider (12), and the opposite ends of the two folding units are The kettle body (1) is in rotary sealed contact, a second heating plate (17) is fixed on the inner wall of the kettle body (1), a motor (4) is fixed on the cover body (2), an output shaft of the motor (4) is fixedly connected to a rotating plate (6) on one side thereof, and the motor (4) can drive the rotating plate (6) to rotate inside the kettle body (1); when the motor (4) drives the rotating plate (6) to rotate, the two folding units are folded and move toward the middle direction of the kettle body (1), and after the folding units move toward the middle direction of the kettle body (1), the two rotating plates (6) and the two folding units divide the inside of the kettle body (1) into a first cavity (13) and a second cavity (14).

2. A distillation apparatus for producing metathesis tetrahydroimine according to claim 1, characterized in that: The folding unit comprises a plurality of folding members, the folding members comprising two baffles (8), the opposite ends of the two baffles (8) are rotatably connected via a connecting plate (15), the opposite ends of the two baffles (8) are in rotatable sealing contact, the lower end of the baffle (8) is in sliding sealing contact with the bottom of the kettle body (1), the two baffles (8) opposite to each other of two adjacent folding members are rotatably connected via a connecting block (11), the two baffles (8) opposite to each other of two adjacent folding members are in rotatable sealing contact, the rotating plate (6) and its adjacent baffles (8) are rotatably connected via a connecting block (11), the connecting block (11) on one side of the rotating plate (6) is fixedly connected to the rotating plate (6), the baffle (8) adjacent to the rotating plate (6) and the connecting block (11) fixed on the rotating plate (6) are elastically rotatably connected, the rotating plate (6) and its adjacent baffles (8) are in rotatable sealing contact, the two adjacent connecting blocks (11) are connected via a spring rod (16), the two adjacent connecting blocks (11) are respectively fixedly connected to the two ends of the spring rod (16); the adjacent two folding units The two baffles (8) are rotatably connected via a connecting piece (18); the two adjacent baffles (8) of the two folding units are rotatably sealed and contacted; a second connecting seat (21) is rotatably connected to the connecting piece (18); the upper end of the second connecting seat (21) is rotatably connected to the first connecting seat (20); the first connecting seat (20) is rotatably connected to the slider (12); a connecting block (11) adjacent to the first connecting seat (20) in one folding unit and the first connecting seat (20) are connected via a spring rod (16); a connecting block (11) adjacent to the second connecting seat (21) in another folding unit and the second connecting seat (21) are connected via a spring rod (16); two ends of the spring rod (16) connecting the first connecting seat (20) and the connecting block (11) are respectively fixedly connected to the first connecting seat (20) and the connecting block (11); and two ends of the spring rod (16) connecting the second connecting seat (21) and the connecting block (11) are respectively fixedly connected to the second connecting seat (21) and the connecting block (11).

3. A distillation apparatus for producing metathesis tetrahydroimine according to claim 2, characterized in that: A third heating plate (19) is fixed on each of the baffles (8).

4. A distillation apparatus for producing metathesis tetrahydroimine according to claim 1, characterized in that: A first heating plate (7) is fixed on each of the rotating plates (6).

5. A distillation apparatus for producing metathesis tetrahydroimine according to claim 1, characterized in that: A first inlet pipe (10) and a second inlet pipe (5) are fixed on the kettle body (1) and are respectively connected to the first cavity (13) and the second cavity (14).

6. A distillation apparatus for producing metathesis tetrahydroimine according to claim 2, characterized in that: The baffle plate (8) adjacent to the rotating plate (6) and the connecting block (11) fixed on the rotating plate (6) are connected via a torsion spring.

7. A method for using a distillation device for producing metathesis tetrahydroimine according to claim 1, characterized in that: Before adding liquid material into the kettle body (1), the two rotating plates (6) are in close contact with the two adjacent inner walls of the kettle body (1), and the two folding units are in an extended state and in close contact with the inner wall of the kettle body (1) on one side thereof. At this time, the first cavity (13) is compressed; liquid material is added to the second cavity (14) in the kettle body (1) and the second heating plate (17) in the second cavity (14) is started. When the second heating plate (17) in the second cavity (14) heats the liquid material in the second cavity (14), the volatilized ethanol is discharged through the discharge pipe (3), and the second cavity (14) is heated. ) is lowered, and the motor (4) is started during the heating process, so that the motor (4) drives the rotating plate (6) and the folding unit to move toward the middle of the kettle body (1). When the rotating plate (6) and the folding unit move toward the middle of the kettle body (1), the folding unit folds, the volume of the second cavity (14) decreases, and the volume of the first cavity (13) gradually increases. During the process of reducing the volume of the second cavity (14), the liquid level of the liquid material in the second cavity (14) can be maintained, thereby preventing the upper portion of the second heating plate (17) in the second cavity (14) from being heated. The liquid material is exposed above the liquid surface and dry burning occurs; after the liquid material in the second cavity (14) is heated, the second heating plate (17) in the second cavity (14) is turned off, and then the heated material in the second cavity (14) is released and cooled to crystallize; then the liquid material is added to the first cavity (13) and the second heating plate (17) in the first cavity (13) is started. When the second heating plate (17) in the first cavity (13) heats the liquid material in the first cavity (13), the volatilized ethanol is discharged through the discharge pipe (3). The liquid level of the liquid material in the first cavity (13) decreases, and the motor (4) is started during the heating process, so that the motor (4) drives the rotating plate (6) and the folding unit to gradually restore. During the process of the motor (4) driving the rotating plate (6) and the folding unit to gradually restore, the volume of the first cavity (13) gradually decreases. During the process of the volume of the first cavity (13) decreasing, the liquid level of the liquid material in the first cavity (13) can be maintained, thereby preventing the upper part of the second heating plate (17) in the first cavity (13) from being exposed above the liquid level of the liquid material and causing dry burning.

Images