A baking device for PCB board processing

Abstract

The present invention belongs to the technical field of PCB processing, and in particular, to a baking device for PCB processing. The present invention provides a baking chamber with openings on both sides, wherein a plurality of conveyor rollers are rotatably disposed within the baking chamber, the ends of the conveyor rollers being connected to a drive group, a plurality of heating lamps being disposed in the middle of the baking chamber, the heating lamps being located above the conveyor rollers, an upper rack being mounted within the baking chamber above the heating lamps, a lower rack being mounted within the baking chamber below the conveyor rollers, an annular insulating belt being rotatably disposed between the upper and lower racks, the outer wall of the insulating belt having two symmetrically distributed notches, and the insulating belt being movable between the upper and lower racks. The present invention bakes the PCB within a relatively sealed area surrounded by the upper and lower racks, thereby preventing a rapid temperature rise resulting from a large amount of heat loss. Furthermore, the insulating belt is constantly in motion, allowing for rapid and even heat distribution.

Description

Technical Field

[0001] The present invention relates to the technical field of PCB board processing, and in particular to a baking device used for PCB board processing. Background Art

[0002] After the PCB board is printed and processed, it needs to be baked. In the prior art, a conveying mechanism is generally used to transport multiple PCB boards into a baking chamber for baking.

[0003] Referring to Chinese patent publication number CN119146712B, a PCB board baking device is disclosed, including a baking oven, wherein a plurality of suspension mechanisms are provided on the inner top of the baking oven, a partition is vertically fixedly provided in the middle of the inner side of the baking oven, a baking mechanism is provided on the front side of the partition, and a cooling mechanism is provided on the rear side of the partition.

[0004] The baking equipment mentioned above and the baking ovens commonly used in the prior art are generally open at both ends to continuously feed the materials for baking. However, this will cause the baking heating position to be directly exposed to the external environment over a large area from both ends, resulting in heat loss at the baking position and affecting the baking efficiency. In order to ensure the baking effect, a long-distance baking operation or increased heat is required, which will result in excessive waste. Summary of the Invention

[0005] Based on the technical problems of the background technology, the present invention proposes a baking device for PCB board processing.

[0006] The present invention proposes a baking device for PCB board processing, comprising a baking chamber with openings on both sides, a plurality of conveying rollers rotatably arranged in the baking chamber, the ends of the conveying rollers being connected to a drive group, a plurality of heating lamps being arranged in the middle position of the baking chamber, the heating lamps being located above the conveying rollers, an upper shelf being installed above the heating lamps in the baking chamber, a lower shelf being installed below the conveying rollers in the baking chamber, an insulating belt with an annular structure being rotatably arranged between the upper and lower shelves, the outer wall of the insulating belt being provided with two symmetrically distributed notches, and the insulating belt moving between the upper and lower shelves.

[0007] Preferably, guide boxes are installed at both ends of the baking chamber, and the guide boxes are configured to be an arc-shaped structure arched in a direction away from the baking chamber.

[0008] Preferably, a chain belt with an annular structure is fixed to the top and bottom ends of the inner side of the thermal insulation belt, and the chain belt located below is connected to the rotating mechanism.

[0009] Preferably, sprocket two is rotatably provided at the four corners of the upper frame plate, and sprocket three is rotatably provided at the four corners of the lower frame plate, and sprocket two and sprocket three are meshed with the chain belt.

[0010] Preferably, the rotating mechanism is provided with a rotating motor installed in the middle position of the bottom of the lower frame plate, the output shaft of the rotating motor extends to the top of the lower frame plate, the output shaft of the rotating motor is fixed with a turntable, the outer wall of the turntable is installed with a gear ring, and the gear ring is engaged with sprocket three.

[0011] Preferably, the guide box is provided with an inner plate and an outer plate, the inner plate is located inside the insulation belt, the outer plate is located outside the insulation belt, and sealing plates are installed at the top and bottom ends between the inner and outer plates.

[0012] Preferably, mounting parts are provided at the top and bottom of the inner plate, and the mounting parts are configured as arc-shaped structures arched toward the baking chamber. Sprocket 1 is rotatably provided at the mounting part, and sprocket 1 is engaged with the chain belt.

[0013] Preferably, the top of the turntable is provided with a plurality of grooves, each group of grooves is distributed in a circular array in the circumferential direction of the turntable, and the plurality of grooves are staggered, and the depth of the grooves gradually decreases in the direction away from the center of the turntable.

[0014] Preferably, a plurality of air entraining mechanisms are provided in the middle of the insulating belt in the baking chamber, the air entraining mechanism is located between two adjacent conveying rollers, and the air entraining mechanism is located below the outer wall of the top of the conveying roller. The air entraining mechanism is provided with a fixed rod fixed to the inner wall of the baking chamber, the fixed rod is arranged parallel to the conveying roller, and both ends of the outer wall of the fixed rod are rotatably connected to a rotating sleeve through a torsion spring, and blades are fixed on both sides of the rotating sleeve.

[0015] Preferably, the blades located between the two rotating sleeves on the same fixed rod are arranged alternately in the circumferential direction, and the blades fixed on the rotating sleeve extend toward the other rotating sleeve. A magnetic block is installed on the top of the turntable, and the magnetic block is magnetically adsorbed to the blades under the fixed rod.

[0016] The beneficial effects of the present invention are:

[0017] In the present invention, when the PCB board enters the corresponding area below the heating lamp tube, the PCB board body is in the middle of the relatively sealed area wrapped by the upper shelf plate, the lower shelf plate and the insulation belt on both sides. The heating lamp tube heats in this area, and the insulation belt seals both sides to prevent a large amount of heat loss and cause the temperature to rise rapidly, thereby improving the baking efficiency. In addition, the insulation belt is always in a moving state. While isolating the openings at both ends of the baking chamber, the movement of the insulation belt can disperse the airflow in this sealed area, so that the temperature in the baking area is quickly and evenly distributed, thereby effectively improving the baking effect and greatly improving the efficiency of the PCB baking operation.

[0018] In the present invention, during the baking operation, sprockets 2 and sprocket 3 at the four corners can be rotated, and the four corners of the chamber surrounded by the upper shelf, the lower shelf and the insulation belt are rotated to induce airflow, and the rotation of the turntable and the movement of the insulation belt perpendicular to the conveying direction are coordinated to evenly disperse the baking airflow, so that the temperature rises quickly and is evenly distributed, thereby improving the efficiency of the baking operation.

[0019] In the present invention, two blades above the fixed rod between two adjacent conveying rollers are opened and closed reciprocally to guide the air flow below the PCB board body, thereby improving the heating efficiency of the heating and baking around the PCB board body and the baking operation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the overall structure of a baking device for PCB board processing proposed by the present invention;

[0021] Figure 2 This is a schematic diagram of the internal structure of a baking chamber of a baking device for PCB board processing proposed by the present invention;

[0022] Figure 3 This is a schematic diagram of the overall planar cross-sectional structure of a baking device for PCB board processing proposed by the present invention;

[0023] Figure 4 This is a schematic diagram of the distribution structure of the upper shelf, lower shelf and guide box of a baking device for PCB board processing proposed by the present invention;

[0024] Figure 5 This is a schematic diagram of the heat insulation belt structure of a baking device for PCB board processing proposed by the present invention;

[0025] Figure 6 This is a schematic diagram of the guide box structure of a baking device for PCB board processing proposed by the present invention;

[0026] Figure 7 This is a schematic diagram of the turntable position structure of a baking device for PCB board processing proposed by the present invention;

[0027] Figure 8 This is a schematic diagram of the distribution structure of the air entrainment mechanism of a baking device for PCB board processing proposed by the present invention;

[0028] Figure 9 This is a schematic structural diagram of an air entrainment mechanism of a baking device for PCB board processing proposed by the present invention;

[0029] Figure 10 This is a schematic diagram of the rotating sleeve and blade structure of a baking device for PCB board processing proposed by the present invention.

[0030] In the figure: 1 baking chamber, 101 top cover, 102 roller hole, 103 lamp trough, 2 conveyor roller, 3 drive group, 4 PCB board, 5 lamp holder, 6 heating lamp tube, 7 upper shelf, 8 lower shelf, 9 insulation belt, 901 notch, 10 chain belt, 11 guide box, 111 inner plate, 112 outer plate, 113 sealing plate, 114 mounting part, 12 sprocket 1, 13 sprocket 2, 14 sprocket 3, 15 rotating motor, 16 gear ring, 17 turntable, 171 groove, 18 magnetic block, 19 air entrainment mechanism, 191 fixing rod, 192 rotating sleeve, 193 blade. DETAILED DESCRIPTION

[0031] Example 1: Reference Figures 1-9 A baking device for PCB board processing includes a baking chamber 1 with openings on both sides. The top of the baking chamber 1 is provided with a detachable top cover 101 to facilitate the maintenance and replacement of internal components. A plurality of conveyor rollers 2 are rotatably arranged in the baking chamber 1. The plurality of conveyor rollers 2 are evenly spaced in the horizontal direction. The ends of the conveyor rollers 2 are connected to a drive group 3. The conveyor rollers 2 are used to convey PCB boards 4. It should be noted that: roller holes 102 corresponding to the positions of the conveyor rollers 2 are opened in the shells at both ends of the baking chamber 1. The ends of the conveyor rollers 2 are rotatably connected to the roller holes 102. The driving group 3 includes a chassis fixed to the outer wall of the baking chamber 1, and a driving motor connected to the conveying roller 2 is installed in the chassis, wherein the conveying rollers 2 corresponding to the chassis can be rotated synchronously by means of a synchronous belt, gears, etc., so that the PCB board 4 is continuously conveyed by a driving motor with the corresponding multiple conveying rollers 2 rotating synchronously. A plurality of heating lamps 6 are arranged in the middle position of the baking chamber 1, and the plurality of heating lamps 6 are distributed at equal distances in the horizontal direction. It should be noted that: lamp troughs 103 are provided at both ends of the baking chamber 1, and lamp holders 5 are installed in the lamp troughs. A heating lamp tube 6 is installed between two lamp holders 5; the heating lamp tube 6 is located above the conveying roller 2, and an upper shelf plate 7 is installed above the heating lamp tube 6 in the baking chamber 1. The two ends of the upper shelf plate 7 are fixed to the inner walls of the two ends of the baking chamber 1. A lower shelf plate 8 is installed below the conveying roller 2 in the baking chamber 1. The two ends of the lower shelf plate 8 are fixed to the inner walls of the two ends of the baking chamber 1. An insulating belt 9 with a ring structure is rotatably arranged between the upper shelf plate 7 and the lower shelf plate 8. The outer wall of the insulating belt 9 is provided with two symmetrically distributed notches 901. The insulating belt 9 is located on both sides between the upper shelf plate 7 and the lower shelf plate 8. The top of the insulation belt 9 is in sliding contact with the bottom of the upper frame plate 7, and the bottom of the insulation belt 9 is in sliding contact with the top of the lower frame plate 8. It should be noted that the heating lamp 6 is arranged in the middle area of the insulation belt 9 of the ring structure, and the end of the conveying roller 2 distributed in the middle area of the insulation belt 9 is separately provided with a driving group 3, so that the insulation belt 9 passes through the outside of the driving group 3 at this position to ensure the effectiveness of the rotation of the insulation belt 9 and the effectiveness of the rotation and conveying of the conveying roller 2 at this position. The insulation belt 9 is between the upper frame plate 7 and the lower frame plate 8 and passes between the two conveying rollers 2.

[0032] When in use, the annular insulating belt 9 rotates between the upper rack plate 7 and the lower rack plate 8. When one of the notches 901 of the insulating belt 9 is facing the feeding port of the baking chamber 1, the notch 901 on the other side of the insulating belt 9 is just facing the discharging port of the baking chamber 1. At this time, the newly-entered PCB board 4 at the feeding position can enter the middle of the insulating belt 9 from the notch 901, and the PCB board 4 originally in the middle position of the insulating belt 9 can be sent out from the notch 901 to the outside of the insulating belt 9; and when the newly-entered PCB board 4 enters the middle area of the insulating belt 9, the insulating belt 9 rotates to rotate the notch 901 away from the baking chamber 1, and the position of the insulating belt 9 in the baking chamber 1 can block both sides. At this time, the PCB board 4 is between the upper rack plate 7 and the lower rack plate 8. The heating lamp 6 is heated in the middle of the relatively sealed area surrounded by the rack 8 and the heat-insulating belt 9. The heat-insulating belt 9 blocks both sides to prevent a large amount of heat loss and a rapid temperature rise, thereby improving the baking efficiency. In addition, while the PCB body 4 is being baked in this area, the heat-insulating belt 9 is always in motion. While isolating the openings at both ends of the baking chamber 1, the movement of the heat-insulating belt 9 disperses the airflow in this sealed area, thereby quickly and evenly distributing the temperature in the baking area. This effectively improves the baking effect and greatly increases the efficiency of the PCB baking operation. When the PCB body 4 is then rotated back into the baking chamber 1 at the notch 901 position, it is sent out, thereby effectively reducing a large amount of heat loss and improving energy utilization.

[0033] It should be noted that: the conveying rate of the conveyor roller 2 and the movement of the insulation belt 9 can be coordinated to set the extension length of the slot 901 to be greater than the width of the PCB board 4. When the insulation belt 9 rotates continuously, the movement rate of the insulation belt 9 and the conveyor roller 2 is coordinated to enable the PCB board 4 to enter the middle position of the insulation belt 9 from the moving slot 901; or the slot 901 can be slightly larger than the width of the PCB board 4. When the PCB board 4 is about to enter or exit, the rotation speed of the insulation belt 9 is accelerated to make the slot 901 move quickly to the corresponding position of the PCB board 4 and stop for a short time. Then, after the PCB board 4 passes through the slot 901, the insulation belt 9 is quickly rotated to move the slot 901 away.

[0034] The guide boxes 11 are provided at both ends of the baking chamber 1, and the guide boxes 11 are provided with an arc-shaped structure that arches in the direction away from the baking chamber 1. The two ends of the guide boxes 11 are provided with openings and the two ends of the guide boxes 11 are sealed with the outer wall of the baking chamber 1. After the insulation belt 9 passes through the baking chamber 1, it moves in the guide boxes 11, so that the annular insulation belt 9 moves from one end of the baking chamber 1 to the other end, enters one of the guide boxes 11, and then enters the baking chamber 1 from the other side, and then moves from the other end of the baking chamber 1 to one end and enters the other guide box 11 again, thereby realizing the circular rotation of the insulation belt 9. On the one hand, the guide boxes 11 of the arc structure ensure the installation and use of the position driving group 3 in this area. On the other hand, the insulation belt 9 rotated to the outside of the baking chamber 1 is protected by the sealing isolation of the guide boxes 11, so as to avoid the heat loss of the insulation belt 9 causing energy waste and affecting the efficiency of the heating and baking of the PCB board 4, and to avoid the contamination of the insulation belt 9 and affecting the quality of the PCB board 4 after baking.

[0035] In the present invention, a chain belt 10 with an annular structure is fixed to the top and bottom ends of the inner side of the insulating belt 9, the inner wall of the guide box 11 is adapted to the insulating belt 9 and the chain belt 10, and the chain belt 10 located below is connected to a rotating mechanism for transmission, and sprocket 2 13 is rotatably provided at the four corners of the upper shelf 7, and sprocket 2 13 is located at the lower position of the upper shelf 7, and sprocket 3 14 is rotatably provided at the four corners of the lower shelf 8, and sprocket 3 14 is located at the upper position of the lower shelf 8, and sprocket 2 13 and sprocket 3 14 are engaged with the chain belt 10 to support the chain belt 10 and the insulating belt 9 through the sprocket 2 13 and sprocket 3 14 distributed up and down at the four corners, and to slide the insulating belt 9 through the guide boxes 11 at both ends, so as to maintain the stability of the insulating belt 9 in the rotating state and the thermal insulation stability on both sides of the baking chamber 1.

[0036] The present invention provides a rotating mechanism with a rotating motor 15 installed at the middle position of the bottom of the lower shelf 8, and the output shaft of the rotating motor 15 extends to the top of the lower shelf 8, and the output shaft of the rotating motor 15 is fixed with a turntable 17, and the outer wall of the turntable 17 is installed with a gear ring 16, which is meshed with the sprocket three 14, so that the rotating motor 15 rotates the gear ring 16 to drive the sprocket three 14 to rotate and drive the chain belt 10 and the insulation belt 9 to rotate, thereby realizing stable rotation of the insulation belt 9, and the rotation of the insulation belt 9 will drive the upper sprocket two 13 to rotate. During the baking operation, the sprocket two 13 and the sprocket three 14 at the four corners can be rotated, and the four corners of the chamber surrounded by the upper shelf 7, the lower shelf 8 and the insulation belt 9 are rotated to induce airflow, and cooperate with the rotation of the turntable 17 and the movement of the insulation belt 9 perpendicular to the conveying direction to evenly disperse the baking airflow, so that the temperature rises quickly and is evenly distributed, thereby improving the baking operation efficiency.

[0037] In the present invention, the guide box 11 is provided with an inner plate 111 and an outer plate 112, the inner plate 111 is located at the inner side of the insulation belt 9, the outer plate 112 is located at the outer side of the insulation belt 9, and the top and bottom ends between the inner plate 111 and the outer plate 112 are installed with a sealing plate 113, the inner side of the insulation belt 9 is slidably fitted with the inner plate 111, the outer side of the insulation belt 9 is slidably fitted with the outer plate 112, the top and bottom ends of the insulation belt 9 are slidably fitted with the sealing plate 113, the top and bottom positions of the inner plate 111 are provided with a mounting portion 114, and the mounting portion 113 is provided with a mounting portion 114. 4 is arranged in an arc-shaped structure arched toward the inside of the baking chamber 1, and a sprocket 12 is rotatably arranged on the mounting portion 114. The sprocket 12 is engaged with the chain belt 10. The engagement of the sprocket 12 with the chain belt 10 outside the baking chamber 1, and the sliding fit between the inner plate 111 and the outer plate 112 and the inner and outer sides of the heat insulating belt 9 ensure the stability of the heat insulating belt 9 when moving outside the baking chamber 1, thereby ensuring the effectiveness of the tensioning movement of the heat insulating belt 9. The detachable arrangement of the inner plate 111, the outer plate 112 and the sealing plate 113 facilitates the removal, replacement or cleaning of the heat insulating belt 9.

[0038] In the present invention, a plurality of groups of grooves 171 are provided on the top of the turntable 17, and each group of grooves 171 is distributed in a circular array in the circumferential direction of the turntable 17, and the plurality of groups of grooves 171 are staggered. The depth of the grooves 171 gradually decreases in the direction away from the center of the turntable 17, so that when the turntable 17 rotates with the gear ring 16, part of the airflow below the conveying roller 2 is directed upward through the grooves 171 with varying depths, and the plurality of groups of grooves 171 are staggered, so that the airflow is dispersed upward, and the movement of the sprocket 2 13 and the sprocket 3 14 and the insulation belt 9 is coordinated to quickly disperse the hot airflow to improve the heating efficiency and the baking operation efficiency.

[0039] Example 2: Reference Figures 1-10, a baking device for PCB board processing, based on Example 1, a plurality of air entrainment mechanisms 19 are provided in the middle of the insulating belt 9 in the baking chamber 1, and the air entrainment mechanism 19 is located between two adjacent conveying rollers 2. It should be noted that an air entrainment mechanism 19 is provided between two adjacent conveying rollers 2, and the air entrainment mechanism 19 is located below the outer wall of the top of the conveying roller 2. The air entrainment mechanism 19 is provided with a fixed rod 191 fixed to the inner wall of the baking chamber 1, and the fixed rod 191 is arranged parallel to the conveying roller 2. Both ends of the outer wall of the fixed rod 191 are rotatably connected to a rotating sleeve 192 through a torsion spring, and blades 193 are fixed on both sides of the rotating sleeve 192. The blades 193 between the two rotating sleeves 192 on the same fixed rod 191 are staggered in the circumferential direction, and the blades 193 fixed on the rotating sleeve 192 extend toward the other rotating sleeve 192, and the fixed blades 193 on the rotating sleeve 192 extend toward the other rotating sleeve 192. The fixed blades 193 do not contact the outer wall of the other rotating sleeve 192. A magnetic block 18 is installed on the top of the turntable 17. The magnetic block 18 is magnetically attracted to the blades 193 under the fixed rod 191. When the turntable 17 rotates, the magnetic block 18 on the turntable 17 moves in the circumferential direction, so that the magnetic block 18 alternately approaches the blades 193 corresponding to different air entrainment mechanisms 19. When the magnetic block 18 approaches the two blades 193 under the fixed rod 191, the two blades 193 under the fixed rod 191 close and bring the two upper blades 193 together. When the magnetic block 18 moves away, the adjacent two blades 193 open under the action of the torsion spring, so that the two blades 193 above the fixed rod 191 between the adjacent two conveying rollers 2 open and close reciprocally, so as to guide the airflow movement under the PCB board body 4, thereby improving the heating efficiency and baking efficiency of the heating and baking around the PCB board body 4.

[0040] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A baking device for PCB board processing, comprising a baking chamber (1) with openings on both sides, a plurality of conveying rollers (2) rotatably arranged in the baking chamber (1), and a drive group (3) connected to the ends of the conveying rollers (2), characterized in that: A plurality of heating lamps (6) are provided in the middle of the baking chamber (1), and the heating lamps (6) are located above the conveying roller (2). An upper shelf (7) is installed above the heating lamps (6) in the baking chamber (1), and a lower shelf (8) is installed below the conveying roller (2) in the baking chamber (1). An annular insulating belt (9) is rotatably provided between the upper shelf (7) and the lower shelf (8), and the outer wall of the insulating belt (9) is provided with two symmetrically distributed notches (901). The insulating belt (9) moves between the upper shelf (7) and the lower shelf (8). A guide box (11) is installed at both ends of the baking chamber (1), and the guide box (11) is configured to be an arc-shaped structure arched in a direction away from the baking chamber (1). The insulating belt (9) The top and bottom ends of the inner side are fixed with a ring-shaped chain belt (10), and the chain belt (10) located below is connected to a rotating mechanism. The four corners of the upper frame plate (7) are all rotatably provided with sprocket two (13), and the four corners of the lower frame plate (8) are all rotatably provided with sprocket three (14). Sprocket two (13) and sprocket three (14) are meshed with the chain belt (10). The rotating mechanism is provided with a rotating motor (15) installed at the middle position of the bottom of the lower frame plate (8). The output shaft of the rotating motor (15) extends to the top of the lower frame plate (8). The output shaft of the rotating motor (15) is fixed with a turntable (17). The outer wall of the turntable (17) is provided with a gear ring (16), which is meshed with the gear ring (16) and the sprocket three (14).

2. A baking device for PCB board processing according to claim 1, characterized in that: The guide box (11) is provided with an inner plate (111) and an outer plate (112), wherein the inner plate (111) is located inside the insulation belt (9), and the outer plate (112) is located outside the insulation belt (9), and sealing plates (113) are installed at the top and bottom ends between the inner plate (111) and the outer plate (112).

3. A baking device for PCB board processing according to claim 2, characterized in that: The inner plate (111) is provided with a mounting portion (114) at the top and bottom positions, and the mounting portion (114) is configured to be an arc-shaped structure arched toward the inside of the baking chamber (1). A sprocket (12) is rotatably provided at the mounting portion (114), and the sprocket (12) is engaged with the chain belt (10).

4. The baking device for PCB board processing according to claim 1, characterized in that: The top of the turntable (17) is provided with a plurality of groups of grooves (171), each group of grooves (171) is distributed in a circular array in the circumferential direction of the turntable (17), and the plurality of groups of grooves (171) are staggered, with the depth of the grooves (171) gradually decreasing in a direction away from the center of the turntable (17).

5. The baking device for PCB board processing according to claim 1, characterized in that: A plurality of air entraining mechanisms (19) are provided in the middle of the insulating belt (9) in the baking chamber (1). The air entraining mechanisms (19) are located between two adjacent conveying rollers (2). The air entraining mechanisms (19) are located below the outer wall of the top of the conveying roller (2). The air entraining mechanisms (19) are provided with a fixed rod (191) fixed to the inner wall of the baking chamber (1). The fixed rod (191) is arranged parallel to the conveying roller (2). Both ends of the outer wall of the fixed rod (191) are rotatably connected to a rotating sleeve (192) through a torsion spring. Blades (193) are fixed to both sides of the rotating sleeve (192).

6. The baking device for PCB board processing according to claim 5, characterized in that: The blades (193) located between the two rotating sleeves (192) on the same fixed rod (191) are arranged alternately in the circumferential direction, and the blades (193) fixed on the rotating sleeve (192) extend toward the other rotating sleeve (192). A magnetic block (18) is installed on the top of the turntable (17), and the magnetic block (18) is magnetically attracted to the blades (193) below the fixed rod (191).

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