A printing filter device with automatic backwashing and recycling function

Abstract

The present invention relates to a printed filter device with an automatic backwashing and recycling function applied to the field of filtration. The two corresponding servo motors are started to rotate the lead screw, driving the movable scraper to fall and scrape the blockage. The blockage is concentrated in the lower part of the filter element, and the content of blockage in the sewage pipe is large. When the movable scraper falls, the electromagnetic ring generates periodic attraction and repulsion on the magnetic rod, driving the paddle plate to fluctuate, thereby avoiding the blockage from agglomerating. Compared with the existing technology, this method reduces the backwashing water consumption and improves the sewage discharge smoothness. When it is detected that the pressure difference reaches the threshold value for the first time and is located below the filter element, the electromagnetic collar is closed, and the wastewater rushes up to cause the scraper to move upward to scrape the blockage and accumulate in the fence space, thereby extending the filtration time of the filter element. When the pressure difference reaches the threshold value again, the servo motor is started to continue backwashing, and the electromagnetic valve and the discharge pipe are opened at the same time to discharge the blockage on the scraper, thereby reducing the backwashing frequency and the waste of water resources.

Description

Technical Field

[0001] The invention relates to a printing filter device, in particular to a printing filter device with an automatic backwashing and recycling function applied in the field of filtration. Background Art

[0002] Printing filtration is a critical step in ensuring the quality of printed products. High-efficiency filtration systems not only improve product quality but also contribute to environmental protection and reduce resource waste. Therefore, selecting the appropriate printing filtration technology and equipment is crucial for producing high-quality printed products and ensuring the sustainable development of the industry.

[0003] The specification of Chinese invention patent CN202311428528.4 discloses an automatic backwash filter. The invention drives the filter element to rotate by a rotating shaft, so that the filter element can expand the contact area with the wastewater, increase the capture capacity of solid particles, and reduce the risk of clogging. At the same time, the rotation inside the filter element can also promote the uniform distribution of wastewater between the filter elements, avoid the problem of excessive flow concentration, and improve the filtration efficiency of sewage. In addition, the specification of Chinese patent CN202410211345.5 discloses a dirt removal filter with automatic backwashing function. The driving mechanism can drive the rotating frame outside the filter element connected to the sewage discharge component to rotate, so that the guide blades rotate along the circumference of the filter element. The guide blades can guide clean water to quickly backwash the filter element, so that the dirt in the filter element connected to the sewage discharge component is discharged outward through the sewage discharge component, which can effectively improve the backwash efficiency of the filter element.

[0004] When the existing backwash filter equipment is working, either the filter element is rotated or the rotating rack outside the filter element is rotated to promote the cleaning efficiency inside the filter element. However, during the backwash process, it is necessary to gradually flush from the top of the filter element to the bottom to remove the blockage inside the filter element. During this process, the content of blockage in the wastewater discharged through the sewage pipe is relatively small, and more clean water is required for backwashing, which easily leads to waste of resources. Summary of the Invention

[0005] In view of the above-mentioned prior art, the technical problem to be solved by the present invention is how to reduce the use of clean water and avoid waste of resources during the backwashing process.

[0006] In order to solve the above problems, the present invention provides a printing filter device with an automatic backwashing and reuse function, comprising a tank body, a liquid inlet and a liquid outlet are provided on the surface of the tank body, and the liquid outlet is located above and to the side of the liquid inlet, a water baffle with a plurality of water outlet holes is installed on the inner wall of the tank body, a filter element corresponding to the water outlet holes is fixed on the top of the water baffle, a curved pipe located below the water baffle is installed at the center position of the circle of the bottom wall of the tank body, a sewage pipe with a tail end extending out of the outside of the tank body is connected to the center position of the bottom of the curved pipe through a shaft sleeve seal, and a sewage valve is installed on the surface of the sewage pipe, an internal hollow rotating arm is installed at the bottom of the tank body, and the top end of the rotating arm is connected to the bottom surface of the curved pipe, a driving motor is installed on one side of the tank body, and the output end of the driving motor is connected to the surface of the rotating arm through a conveyor belt;

[0007] A servo motor corresponding to the filter element is installed on the top of the tank body. The output end of the servo motor is connected to a screw located in the filter element. A movable scraper with the same inner diameter as the filter element is threaded on the surface of the screw. A receiving groove is provided on the outside of the screw. An electromagnetic ring arranged concentrically with the screw is fixed inside the receiving groove. A magnetic rod is slidably connected to the inside of the receiving groove. A toggle piece is movably installed on the bottom of the movable scraper through a bracket, and the tail end of the magnetic rod is movably connected to the surface of the toggle piece.

[0008] In the above-mentioned printing filter equipment with automatic backwashing and reuse function, the cooperation of the servo motor, movable scraper, electromagnetic ring, magnetic rod and toggle plate can increase the content of blockages in the sewage pipe during backwashing, thereby reducing the water consumption during backwashing and achieving energy-saving effect.

[0009] As a further improvement of the present application, the two water outlets of the bent pipe correspond to two water outlet holes on the same diameter axis in the water baffle, and the diameter of the water outlet is the same as the diameter of the water outlet hole, and the liquid inlet is located below the water baffle.

[0010] As a further improvement of the present application, the length of the threaded area on the surface of the screw is smaller than the height of the filter element, and the distance between the bottom end of the threaded area and the bottom end of the filter element is not smaller than the height of the toggle plate.

[0011] As a further improvement of the present application, the number of filter elements is an even number, and the two servo motors on the same diameter axis are electrically connected.

[0012] As a further improvement of the present application, an image collector is embedded in the bottom of the movable scraper, and the image collector is located between two adjacent shifting plates, and pressure sensors are installed on the inner and outer walls of the filter element.

[0013] As a further improvement of the present application, a backwash control system is also included. The backwash control system includes a processor installed on the surface of the tank body, and the processor is connected to an image acquisition module, a start-up execution module and a backwash execution module. The image acquisition module is connected to the image acquisition signal for checking the density of the blockage in the filter element when the movable scraper descends. The start-up execution module is connected to the pressure sensor signal for monitoring the pressure difference inside and outside the filter element as a reference for starting backwashing. The backwash execution module is connected to the servo motor, electromagnetic ring and drain valve signal for performing backwashing operations.

[0014] As another improvement of the present application, the bottom end of the lead screw is a magnetic rod, a float is sleeved on the outer side of the magnetic rod, an electromagnetic ring with a built-in displacement sensor is sleeved on the outer surface of the magnetic rod, a scraper is installed on the outer side of the electromagnetic ring through a connecting rod, and a discharge pipe with a solenoid valve mounted on the surface is installed through the inside of the scraper.

[0015] As another improved supplement of the present application, the outer diameter of the scraper is the same as the inner diameter of the filter element, and a fence is installed on the top of the scraper surface facing away from the filter element.

[0016] As another improved supplement to the present application, two point-symmetrically arranged baffles are installed at the bottom of the movable scraper, and the vertical projection of the baffles is located on the inner side of the scraper, the length of the baffles is greater than the height of the toggle plate, and the baffles are located in the gap between the two adjacent toggle plates.

[0017] To sum up, the present application starts the corresponding two servo motors to rotate the lead screw, driving the movable scraper to fall and scrape off the blockage. The blockage is concentrated in the lower part of the filter element, and the sewage pipe contains a lot of blockage. When the movable scraper falls, the electromagnetic ring produces periodic attraction and repulsion on the magnetic rod, driving the paddle to fluctuate, avoiding the blockage from agglomerating. Compared with the existing technology, this method reduces the backwash water consumption and improves the smoothness of sewage discharge. When it is detected that the pressure difference reaches the threshold for the first time and is located below the filter element, the electromagnetic ring is closed, and the wastewater rushes up to cause the scraper to move up to scrape off the blockage and accumulate in the fence space, extending the filtration time of the filter element. When the pressure difference reaches the threshold again, the servo motor is started to continue backwashing, and the solenoid valve and the discharge pipe are opened at the same time to discharge the blockage on the scraper, reducing the backwash frequency and water waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the overall structure of the first embodiment of this application;

[0019] Figure 2 This is a bottom view of the tank body according to the first embodiment of the present application;

[0020] Figure 3 This is a schematic diagram of the internal structure of the tank according to the first embodiment of the present application;

[0021] Figure 4 This is a diagram of the internal structure of the filter element according to the first embodiment of the present application;

[0022] Figure 5 This is a schematic diagram of the internal structure of the movable scraper according to the first embodiment of the present application;

[0023] Figure 6 This is a state diagram of blockage accumulation and sewage discharge when the movable scraper falls in the first embodiment of the present application;

[0024] Figure 7 This is a state diagram of the toggle piece in the first embodiment of the present application;

[0025] Figure 8 This is a schematic diagram of the installation of the floater and the baffle rod according to the second embodiment of the present application;

[0026] Figure 9 This is a schematic diagram of the floater composition of the second embodiment of the present application;

[0027] Figure 10 This is a schematic diagram of the installation of the movable scraper and the baffle rod according to the second embodiment of the present application;

[0028] Figure 11 This is a schematic diagram of the upward movement of the floater according to the second embodiment of the present application.

[0029] Description of the numbers in the figure:

[0030] 1. Tank body; 101. Liquid inlet; 102. Liquid outlet; 2. Drain pipe; 3. Rotating arm; 4. Drive motor; 5. Filter element; 51. Lead screw; 52. Movable scraper; 521. Paddle; 522. Magnetic rod; 523. Electromagnetic ring; 524. Receiving groove; 6. Water baffle; 7. Bend pipe; 8. Servo motor; 9. Floater; 91. Electromagnetic collar; 92. Scraper; 10. Stop rod. DETAILED DESCRIPTION

[0031] Two implementation modes of the present application are described in detail below with reference to the accompanying drawings.

[0032] The first implementation method:

[0033] Figure 1-3The invention shows a printing filter device with automatic backwashing and reuse function, comprising a tank body 1, a liquid inlet 101 and a liquid outlet 102 provided on the surface of the tank body 1, and the liquid outlet 102 is located above and to the side of the liquid inlet 101, a water baffle 6 with multiple water outlet holes installed on the inner wall of the tank body 1, a filter element 5 corresponding to the water outlet holes is fixed on the top of the water baffle 6, a curved pipe 7 located below the water baffle 6 is installed at the center position of the circle of the bottom wall of the tank body 1, a sewage pipe 2 with its tail end extending out of the outside of the tank body 1 is connected to the bottom center position of the curved pipe 7 through a shaft sleeve seal, and a sewage valve is installed on the surface of the sewage pipe 2, a hollow rotating arm 3 is installed at the bottom of the tank body 1, and the top end of the rotating arm 3 is connected to the bottom surface of the curved pipe 7, a driving motor 4 is installed on one side of the tank body 1, and the output end of the driving motor 4 is connected to the surface of the rotating arm 3 through a conveyor belt;

[0034] Figure 4-5 It is shown that a servo motor 8 corresponding to the filter element 5 is installed on the top of the tank body 1, and the output end of the servo motor 8 is connected to the screw 51 located in the filter element 5. The surface of the screw 51 is threadedly sleeved with a movable scraper 52 with the same inner diameter as the filter element 5. The interior of the movable scraper 52 is provided with a receiving groove 524 located on the outside of the screw 51, and the interior of the receiving groove 524 is fixed with an electromagnetic ring 523 arranged concentrically with the screw 51. The interior of the receiving groove 524 is slidably connected with a magnetic rod 522, and the bottom of the movable scraper 52 is movably mounted with a toggle piece 521 through a bracket, and the tail end of the magnetic rod 522 is movably connected to the surface of the toggle piece 521.

[0035] Specifically, after the wastewater after printing filtration is transported to the interior of the tank body 1 through the liquid inlet 101, it enters the interior of the filter element 5 through the water outlet hole. After being filtered by the filter element 5, the residue and other blockages are left in the filter element 5. The filtered water is discharged from the interior of the tank body 1 through the liquid outlet 102.

[0036] During the backwashing operation, the driving motor 4 is started to drive the rotating arm 3 to rotate. Since the top end of the rotating arm 3 is connected to the elbow 7, the rotating arm 3 can drive the elbow 7 to rotate synchronously when rotating, and dock with the positions of the two filter elements 5 on the same diameter line. Then, the driving motor 4 is turned off and the corresponding two servo motors 8 are started (the two started servo motors 8 are on the same straight line with the two filter elements 5 corresponding to the water outlet of the elbow 7), driving the screw 51 in the filter element 5 to rotate, thereby driving the movable scraper 52 originally located near the top part of the filter element 5 to fall;

[0037] During the falling process of the movable scraper 52, the blockage on the inner wall of the filter element 5 will be scraped off. As the movable scraper 52 falls, the blockage in the filter element 5 gradually concentrates on the lower part of the filter element 5 (such as Figure 6As shown), the drain valve is then started, and the filtered water in the tank body 1 backwashes the filter element 5. At the same time, since the blockages are more concentrated in the lower part of the filter element 5, the blockage content discharged into the drain pipe 2 at this time is relatively high. Compared with the single top-down flushing operation in the prior art, the consumption of filtered water during backwashing can be reduced. In addition, during the falling process of the movable scraper 52, the working state of the electromagnetic ring 523 is switched to cause it to produce a periodic attraction and repulsion effect on the magnetic rod 522, thereby driving the toggle piece 521 to fluctuate in the filter element 5. When the blockage content in the filter element 5 is relatively high, the blockage is toggled to avoid agglomeration and affecting the smoothness of the sewage discharge from the drain pipe 2 (as shown). Figure 7 shown).

[0038] The two water outlets of the curved pipe 7 correspond to two water outlet holes on the same diameter axis in the water baffle 6 , and the diameter of the water outlet is the same as that of the water outlet hole. The liquid inlet 101 is located below the water baffle 6 .

[0039] Specifically, the two water outlets of the bend pipe 7 are designed so that each time the bend pipe 7 switches to align with the water outlet, it can simultaneously perform backwashing and sewage treatment in the two filter elements 5, thereby improving the efficiency of backwashing. In addition, the sewage pipe 2 is connected to the bend pipe 7 through a bearing sleeve, and the rotating arm 3 is designed to be hollow inside. Therefore, when the rotating arm 3 drives the bend pipe 7 to rotate, it will not affect the sewage pipe 2.

[0040] The length of the threaded area on the surface of the screw 51 is smaller than the height of the filter element 5 , and the distance between the bottom end of the threaded area and the bottom end of the filter element 5 is not smaller than the height of the toggle piece 521 .

[0041] Specifically, since there is a gap between the bottom end of the threaded area and the bottom of the filter element 5 , when the movable scraper 52 moves to the bottom position of the threaded area, the paddle 521 still has space to move.

[0042] The number of filter elements 5 is an even number, and the two servo motors 8 on the same diameter axis are electrically connected.

[0043] Specifically, when the filter element 5 is undergoing backwashing, two servo motors 8 on the same diameter are started synchronously to drive the movable scraper 52 in the corresponding filter element 5 to fall.

[0044] An image collector is embedded in the bottom of the movable scraper 52 and is located between two adjacent shifting pieces 521 . Pressure sensors are installed on both the inner and outer walls of the filter element 5 .

[0045] It also includes a backwash control system, which includes a processor installed on the surface of the tank body 1. The processor is connected to an image acquisition module, a start-up execution module and a backwash execution module. The image acquisition module is connected to the image acquisition signal for checking the density of the blockage in the filter element 5 when the movable scraper 52 descends. The start-up execution module is connected to the pressure sensor signal for monitoring the pressure difference between the inside and outside of the filter element 5 as a reference for starting backwashing. The backwash execution module is connected to the servo motor 8, the electromagnetic ring 523 and the drain valve signal for performing backwashing operations.

[0046] Specifically, when the image collector follows the falling of the movable scraper 52, if it detects that the blockage distribution below the movable scraper 52 is relatively dense (the density can be set by the threshold value), it can temporarily stop the rotation of the servo motor 8, interrupt the falling and scraping operations of the movable scraper 52, and avoid blockage of the sewage pipe due to excessive blockage content during sewage discharge.

[0047] The second implementation method:

[0048] Figure 8-10 It is shown that the bottom end of the lead screw 51 is a magnetic rod, the outer side of the magnetic rod is sleeved with a floater 9, the outer surface of the magnetic rod is sleeved with an electromagnetic ring 91 with a built-in displacement sensor, the outer side of the electromagnetic ring 91 is installed with a scraper 92 through a connecting rod, and the inside of the scraper 92 is penetrated by a discharge pipe with a solenoid valve installed on the surface.

[0049] The outer diameter of the scraper 92 is the same as the inner diameter of the filter element 5 , and a fence is installed on the top of the scraper 92 facing away from the filter element 5 .

[0050] Two point-symmetrically arranged baffles 10 are installed at the bottom of the movable scraper 52, and the vertical projection of the baffle 10 is located on the inner side of the scraper 92. The length of the baffle 10 is greater than the height of the toggle plate 521, and the baffle 10 is located in the gap between the two adjacent toggle plates 521.

[0051] Different from the first embodiment, this embodiment is that, in the first embodiment, the inner wall of the lower part of the filter element 5 is easily clogged first due to the filtering and discharge of printing wastewater from top to bottom, and then the backwashing pressure threshold is reached, and then the backwashing operation is started. However, at this time, the pressure difference between the inner and outer walls of the upper part of the filter element 5 has not reached the pressure threshold. At this time, the filter element 5 still has filtering capacity, but the backwashing operation will increase the backwashing frequency, resulting in waste of resources.

[0052] Specifically, in this embodiment, a plurality of pressure sensors are distributed vertically on the inner and outer surfaces of the filter element 5. When the pressure difference detected by the pressure sensors on the surface of the filter element 5 reaches the pressure threshold for the first time, the position of the pressure sensor is determined. If the pressure sensor is at the lower position of the filter element 5, the electromagnetic ring 91 is closed at this time. Under the upward impact of the wastewater entering the liquid inlet 101, the scraper 92 moves upward and scrapes off the blockage on the inner wall of the filter element 5 and accumulates it in the space formed by the fence. After that, the scraper 92 moves upward and is intercepted by the blocking rod 10 and is located below the movable scraper 52 (as shown in FIG. Figure 11 As shown), the blockage on the inner wall of the filter element 5, especially the inner wall at the lower position, is cleaned, so that the filter element 5 can continue the filtering operation for a period of time. After that, when the pressure difference between the inside and outside of the filter element 5 reaches the pressure threshold, the servo motor 8 is started to continue the backwashing operation (during the backwashing process, under the action of the blocking rod 10, the scraper 92 is synchronously lowered). At the same time, the solenoid valve is started to open the discharge pipe, and the blockage on the scraper 92 is discharged to the bottom of the scraper 92 and then discharged, thereby reducing the frequency of backwashing and reducing the waste of water resources.

[0053] The electromagnetic collar 91 moves to the position of the magnetic rod, and the displacement sensor sends a start signal to the electromagnetic collar 91 . At this time, the electromagnetic collar 91 and the magnetic rod attract each other, thereby constraining the floater 9 .

[0054] In summary, the present application starts the corresponding two servo motors 8, causing the screw 51 in the filter element 5 to rotate, driving the movable scraper 52 to fall and scrape off the blockage, starting the drain valve, and using the filtered water in the tank body 1 for backwashing. The blockage is concentrated in the lower part of the filter element 5, and the blockage content in the drain pipe 2 is high. When the movable scraper 52 falls, the electromagnetic ring 523 produces periodic attraction and repulsion on the magnetic rod 522, driving the toggle plate 521 to fluctuate, and avoid the blockage from agglomerating. Compared with the prior art, this method reduces the backwash water consumption and improves the smoothness of sewage discharge. When it is detected that the pressure difference reaches the threshold for the first time and is located below the filter element 5, the electromagnetic sleeve 91 is closed, and the wastewater rushes up to cause the scraper 92 to move up to scrape off the blockage and accumulate in the fence space, extending the filtration time of the filter element 5. When the pressure difference reaches the threshold again, the servo motor 8 is started to continue backwashing, and the electromagnetic valve and the discharge pipe are opened at the same time to discharge the blockage on the scraper 92, reducing the backwash frequency and water waste.

[0055] In view of current actual needs, the protection scope of the above-mentioned implementation mode adopted in this application is not limited to this. Various changes made within the knowledge scope of technical personnel in this field without departing from the concept of this application still fall within the protection scope of the present invention.

Claims

1. A printing filter device with an automatic backwashing and recycling function, comprising a tank body (1), wherein a liquid inlet (101) and a liquid outlet (102) are provided on the surface of the tank body (1), and the liquid outlet (102) is located above and to the side of the liquid inlet (101), and characterized in that: The inner wall of the tank body (1) is provided with a water baffle (6) with a plurality of water outlet holes built therein, a filter element (5) corresponding to the water outlet holes is fixed on the top of the water baffle (6), a curved pipe (7) located below the water baffle (6) is provided at the center of the circle of the bottom wall of the tank body (1), a sewage pipe (2) whose tail end extends out of the outside of the tank body (1) is connected to the bottom of the curved pipe (7) through a sleeve seal, and a sewage valve is provided on the surface of the sewage pipe (2), an internal hollow rotating arm (3) is provided at the bottom of the tank body (1), and the top end of the rotating arm (3) is connected to the bottom surface of the curved pipe (7), a driving motor (4) is provided on one side of the tank body (1), and the output end of the driving motor (4) is connected to the surface of the rotating arm (3) through a conveyor belt; A servo motor (8) corresponding to the filter element (5) is installed on the top of the tank body (1), the output end of the servo motor (8) is connected to a lead screw (51) located in the filter element (5), the surface of the lead screw (51) is threadedly sleeved with a movable scraper (52) having the same inner diameter as the filter element (5), the interior of the movable scraper (52) is provided with a receiving groove (524) located outside the lead screw (51), the interior of the receiving groove (524) is fixed with an electromagnetic ring (523) arranged concentrically with the lead screw (51), the interior of the receiving groove (524) is slidably connected with a magnetic rod (522), the bottom of the movable scraper (52) is movably mounted with a toggle plate (521) through a bracket, and the tail end of the magnetic rod (522) is movably connected to the surface of the toggle plate (521); The electromagnetic ring (523) generates periodic attraction and repulsion effects on the magnetic rod (522), thereby driving the paddle (521) to paddle in the filter element (5). When the amount of blockage in the filter element (5) is high, the blockage is paddled to avoid agglomeration.

2. The printing filter equipment with automatic backwashing and reuse function according to claim 1, characterized in that: The two water outlets of the curved pipe (7) correspond to two water outlet holes on the same diameter axis in the water baffle (6), and the diameter of the water outlet is the same as the diameter of the water outlet hole. The liquid inlet (101) is located below the water baffle (6).

3. The printing filter equipment with automatic backwashing and reuse function according to claim 1, characterized in that: The length of the threaded area on the surface of the lead screw (51) is less than the height of the filter element (5), and the distance between the bottom end of the threaded area and the bottom end of the filter element (5) is not less than the height of the toggle piece (521).

4. The printing filter equipment with automatic backwashing and reuse function according to claim 1, characterized in that: The number of the filter elements (5) is an even number, and the two servo motors (8) on the same diameter axis are electrically connected.

5. The printing filter equipment with automatic backwashing and recycling function according to claim 1 is characterized in that: An image collector is embedded in the bottom of the movable scraper (52), and the image collector is located between two adjacent shifting pieces (521). Pressure sensors are installed on the inner and outer walls of the filter element (5).

6. The printing filter equipment with automatic backwashing and recycling function according to claim 5, characterized in that: The backwashing control system includes a processor installed on the surface of the tank body (1), and the processor is connected to an image acquisition module, a start-up execution module, and a backwashing execution module. The image acquisition module is connected to the image acquisition signal for checking the density of the blockage in the filter element (5) when the movable scraper (52) descends. The start-up execution module is connected to the pressure sensor signal for monitoring the pressure difference between the inside and outside of the filter element (5) as a reference for starting backwashing. The backwashing execution module is connected to the servo motor (8), the electromagnetic ring (523), and the drain valve signal for performing the backwashing operation.

7. The printing filter equipment with automatic backwashing and reuse function according to claim 1, characterized in that: The bottom end of the lead screw (51) is a magnetic rod, the outer side of the magnetic rod is sleeved with a floater (9), the outer surface of the magnetic rod is sleeved with an electromagnetic collar (91) with a built-in displacement sensor, the outer side of the electromagnetic collar (91) is installed with a scraper (92) through a connecting rod, and the interior of the scraper (92) is penetrated by a discharge pipe with a surface-mounted electromagnetic valve.

8. The printing filter equipment with automatic backwashing and recycling function according to claim 7, characterized in that: The outer diameter of the scraper (92) is the same as the inner diameter of the filter element (5), and a fence is installed on the top of the surface of the scraper (92) facing away from the filter element (5).

9. The printing filter equipment with automatic backwashing and recycling function according to claim 8, characterized in that: Two point-symmetrically arranged blocking rods (10) are installed at the bottom of the movable scraper (52), and the projection of the blocking rod (10) in the vertical direction is located on the inner side of the scraper (92). The length of the blocking rod (10) is greater than the height of the toggle plate (521), and the blocking rod (10) is located in the gap between two adjacent toggle plates (521).

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