Reprocessed plastic gradient impurity removal mold and method

Abstract

The invention discloses a recycled plastic gradient impurity removal mold and method in the field of recycled plastic recycling and processing, and the recycled plastic gradient impurity removal mold comprises an impurity removal machine and an extruder, and further comprises a transfer cylinder used for connecting the impurity removal machine and the extruder; the transfer cylinder is provided with a main exhaust hole and a pneumatic pump; the main exhaust hole can be used for exhausting gas in the cavity of the transfer cylinder when the transfer cylinder is used for feeding; the product forming quality is guaranteed, the production efficiency is improved, and the mold and equipment are protected; the pneumatic pump can seal the main exhaust hole when feeding in the transfer cylinder is stopped, meanwhile, high-pressure gas is injected into the transfer cylinder, and continuous and sufficient extrusion thrust is applied to molten plastic in the transfer cylinder through gas pressure, so that a plastic strip extruded by the extruder is kept in a continuous form, and breakage is avoided; through linkage of the pneumatic pump pressurizing assembly and the sealing assembly, when the impurity removing machine stops, sealing of the transfer cylinder is achieved, high-pressure gas is injected, continuous thrust is applied to residual molten plastic in the cylinder, continuous feeding of raw materials of the extruder is guaranteed, and plastic strips are prevented from being broken.

Description

Technical Field

[0001] This invention relates to the field of recycled plastics processing, specifically to a gradient impurity removal mold and method for recycled plastics. Background Technology

[0002] In the field of recycled plastics processing, recycled plastics need to undergo gradient impurity removal by a decontamination machine before being extruded into shape by a die in an extruder. The filter screen of the decontamination machine is the core component that ensures the impurity removal effect. However, the filter screen is prone to clogging due to impurities during long-term use, which leads to a decrease in filtration efficiency, and the machine must be shut down periodically for replacement.

[0003] In traditional production equipment, the filter and extruder are often directly connected or have a simple transfer structure. When the filter is shut down to replace the filter screen, the supply of plastic raw materials is interrupted. Due to the lack of continuous raw material input, the residual plastic inside the extruder will be extruded out in a short time, causing the subsequently extruded plastic strips to break due to the lack of raw material supply. In addition, during the shutdown to replace the filter screen, the transfer structure lacks an effective sealing and pressurization mechanism, and cannot apply continuous thrust to the residual plastic, making the problem of material interruption in the extruder more prominent. This not only causes a large amount of waste, but also requires shutdown and readjustment of the extruder to restore the continuity of plastic strips, seriously affecting production efficiency and processing costs.

[0004] Based on this, the present invention designs a gradient impurity removal mold and method for recycled plastics to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a gradient impurity removal mold and method for recycled plastics to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a gradient impurity removal mold for recycled plastics, comprising an impurity removal machine and an extruder, and further comprising a transfer cylinder for connecting the impurity removal machine and the extruder; The transfer cylinder is equipped with a main exhaust port and an air pressure pump. The main vent hole can discharge the gas inside the cavity of the transfer cylinder when the transfer cylinder is being fed; thus ensuring product molding quality, improving production efficiency, and protecting the mold and equipment. When the feed stops in the intermediate drum, the pneumatic pump can seal the main exhaust port and inject high-pressure gas into the intermediate drum. The gas pressure applies a continuous and sufficient extrusion thrust to the molten plastic in the intermediate drum, thereby maintaining the continuous shape of the plastic strip extruded by the extruder and preventing breakage.

[0007] As a further embodiment of the present invention, the transfer cylinder is provided with a secondary exhaust port, which can be opened in conjunction with the main exhaust port to improve the exhaust efficiency of the transfer cylinder; when the pressure of the plastic injected into the transfer cylinder decreases and the exhaust demand decreases, the main exhaust port is closed and the secondary exhaust port remains open to meet the basic exhaust demand. The main exhaust port and the auxiliary exhaust port are equipped with sealing components.

[0008] As a further aspect of the present invention, the sealing assembly includes a main exhaust channel arranged in a circumferential array within the main exhaust hole; A sealing plug is slidably connected in the vertical direction inside the main exhaust port to seal the main exhaust channel. A pressure spring is fixedly connected to the upper surface of the piston. The upper end of the pressure spring is fixedly connected to the inner top wall of the main exhaust port. The top of the main exhaust port is in a sealed state. The upper end of the secondary exhaust port is sealed, and a secondary exhaust channel is formed in a circumferential array on its inner wall. A sealing plug is slidably connected in the upper and lower direction inside the secondary exhaust port to seal the secondary exhaust channel.

[0009] As a further embodiment of the present invention, the pneumatic pump also includes a pressurizing component, which enables the main exhaust port and the auxiliary exhaust port to close synchronously when the intermediate drum stops feeding, thereby creating a sealed environment at the upper end of the intermediate drum; then the pneumatic pump injects high-pressure gas into the intermediate drum, and applies a continuous and sufficient extrusion thrust to the molten plastic in the drum through the gas pressure, thereby keeping the plastic strip extruded by the extruder in a continuous molding shape. The pressurization assembly includes a pressurization chamber fixedly connected to the outlet of a pneumatic pump. Two air guide pipes are fixedly connected to both sides of the pressurization chamber. The outlets of the two air guide pipes are respectively connected to the interior of the main exhaust port and the auxiliary exhaust port. An air outlet block is fixedly connected to the outlet of the air guide pipe located in the auxiliary exhaust port. When the rotating drum stops feeding, the pneumatic pump can inject gas into the main exhaust port and the auxiliary exhaust port through the air pipes. The air pressure presses the sealing plugs one and two downwards, preventing them from shifting and disengaging them from the main exhaust channel and the auxiliary exhaust channel. The lower end of the pressurization chamber is sealed with a pressure control valve.

[0010] As a further embodiment of the present invention, the transfer cylinder further includes a fixing rod fixedly connected to its inner wall along its central axis, and a conical block is elastically slidably connected to the fixing rod near the feed inlet of the transfer cylinder by a spring. The conical block is initially sealed and fitted to the feed inlet of the transfer cylinder.

[0011] As a further embodiment of the present invention, the intermediate drum further includes a feed pipe and a discharge pipe, wherein the first and last ends of the feed pipe are fixedly and sealed to the discharge port of the impurity remover and the feed port of the intermediate drum; the first and last ends of the discharge pipe and the discharge port of the intermediate drum are fixedly and sealed to the feed port of the extruder.

[0012] As a further embodiment of the present invention, the lower end of the transfer cylinder is tapered.

[0013] A gradient impurity removal method for recycled plastics, the method being as follows: S1: The melted plastic is introduced into the impurity removal machine for impurity removal; S2: The plastic after impurity removal in the impurity remover is introduced into the transfer cylinder for transfer, so as to realize the uninterrupted conveying of plastic to the extruder. The extruder is equipped with a special mold for extruding plastic into strips. S3: The extruder continuously extrudes molten plastic into strips through its internal mold.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. By linking the air pressure pump pressurization component and the sealing component, the transfer cylinder is sealed and high-pressure gas is injected when the impurity removal machine stops, applying continuous thrust to the residual molten plastic in the cylinder, ensuring a continuous supply of raw materials to the extruder and preventing the plastic strip from breaking.

[0015] 2. By coordinating and switching between the main and auxiliary exhaust ports, the exhaust efficiency can be dynamically adjusted to adapt to the feeding status, thus avoiding exhaust problems that could exacerbate the instability of raw material supply.

[0016] 3. The automatic opening and closing and sealing of the feed inlet can be achieved by the cooperation of the conical block and the spring, which can prevent impurities from contaminating the raw materials or gas leakage from affecting the pressure stability, reduce the generation of waste products and downtime for debugging, and ultimately improve production continuity, product forming quality and processing efficiency, and reduce production costs. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the structure on the rotating cylinder in this invention; Figure 3 for Figure 2 Enlarged schematic diagram of the structure at point A in the middle; Figure 4 This is a schematic diagram of the half-section structure of the rotating cylinder in this invention; Figure 5 This is a schematic diagram of the internal structure of the main exhaust port and the auxiliary exhaust port of the present invention; Figure 6 The positions of the normal pressure feed sealing plug one and sealing plug two in the rotating drum of this invention are shown. Structural diagram; Figure 7 The positions of the feed sealing plug one and sealing plug two in the rotating drum pressure reduction of this invention are shown. Structural diagram; Figure 8 This is a schematic diagram showing the position and structure of the rotary drum stop feeding sealing plug one and sealing plug two in this invention; Figure 9 This is a schematic diagram of the process method of the present invention; In the attached diagram, the components represented by each number are as follows: 1. Impurity remover; 2. Extruder; 3. Transmission cylinder; 4. Main exhaust port; 5. Air pressure pump; 6. Secondary exhaust port; 7. Main exhaust channel; 8. Sealing plug one; 9. Pressure spring; 10. Secondary exhaust channel; 11. Sealing plug two; 12. Pressurization chamber; 13. Air guide pipe; 14. Air outlet block; 15. Pressure control valve; 16. Fixing rod; 17. Conical block; 18. Feed pipe; 19. Discharge pipe. Detailed Implementation

[0018] Please see Figures 1-9 The present invention provides a technical solution: a gradient impurity removal mold for recycled plastic, including an impurity removal machine 1 and an extruder 2, and also including a transfer cylinder 3 for connecting the impurity removal machine 1 and the extruder 2; The transfer cylinder 3 is provided with a main exhaust port 4 and an air pressure pump 5. The main exhaust port 4 can discharge the gas inside the cavity of the transfer cylinder 3 when the transfer cylinder 3 is being fed; thus ensuring product molding quality, improving production efficiency, and protecting the mold and equipment. When the air pump 5 stops feeding into the intermediate drum 3, it can seal the main exhaust port 4 and inject high-pressure gas into the intermediate drum 3. The gas pressure is used to apply a continuous and sufficient extrusion thrust to the molten plastic in the intermediate drum 3, so that the plastic strip extruded by the extruder 2 maintains a continuous shape and avoids breakage.

[0019] After being processed by the impurity remover 1, the recycled plastic enters the intermediate drum connecting the impurity remover and the extruder 2. When the intermediate drum is in the feeding state, the air pump 5 is turned off, and the main exhaust port 4 is opened simultaneously to promptly discharge the gas squeezed out of the cavity due to plastic filling, including air and trace amounts of volatile gas generated by the plastic melting, providing space for smooth plastic filling. When the impurity remover 1 needs to replace the filter screen, the feeding needs to be stopped. At this time, the intermediate drum 3 stops feeding, the air pump 5 starts, first sealing the main exhaust port 4 to block the exhaust channel, and then injecting high-pressure gas into the intermediate drum 3. The high-pressure gas applies a continuous and sufficient extrusion thrust to the molten plastic in the drum, pushing the plastic stably into the extruder, ensuring that the extruder always receives a continuous supply of plastic.

[0020] The main vent 4 vents air during feeding, which can prevent gas from accumulating and causing defects such as air bubbles and material shortages in the plastic, ensuring the molding quality of the plastic strips extruded later. At the same time, it reduces the obstruction of gas to plastic filling and improves feeding efficiency. Meanwhile, the air pump 5 maintains the plastic supply with high-pressure gas when the material is stopped, which can effectively prevent the plastic strip from breaking due to the interruption of the feed in the extruder, reduce downtime for adjustment, ensure production continuity, and the exhaust function can prevent the high pressure of the cavity gas from impacting the transfer cylinder 3. The synergistic effect of sealing and pressurization can also reduce the load fluctuation of the extruder and reduce equipment wear.

[0021] As a further embodiment of the present invention, the transfer cylinder 3 is provided with a secondary exhaust port 6, which can be opened in conjunction with the main exhaust port 4 to improve the exhaust efficiency of the transfer cylinder 3; when the pressure of the plastic injected into the transfer cylinder 3 decreases and the exhaust demand decreases, the main exhaust port 4 is closed and the secondary exhaust port 6 remains open to meet the basic exhaust demand. The main exhaust port 4 and the auxiliary exhaust port 6 are equipped with sealing components.

[0022] When the transfer cylinder 3 is in the feeding stage and plastic is continuously injected into the cavity, the main vent 4 and the auxiliary vent 6 open together to discharge the gas squeezed out of the cavity due to the plastic filling. The dual venting channels increase the overall venting rate and ensure that the gas is discharged quickly without stagnation. When the pressure of the plastic injected into the transfer cylinder 3 decreases, it means that the venting demand decreases accordingly. At this time, the main vent 4 closes to reduce the venting volume, while the auxiliary vent 6 remains open to continuously discharge a small amount of residual gas inside the cavity to meet the basic venting requirements.

[0023] When the main and auxiliary vents open in tandem, the venting rate is significantly improved, preventing excessive gas accumulation that could hinder plastic filling and shortening the feeding cycle. Regarding venting accuracy, the venting mode is switched according to changes in plastic pressure. Closing the main vent 4 and allowing the auxiliary vent 6 to operate independently prevents excessive venting and pressure loss when the plastic pressure inside the transfer cylinder 3 decreases. Simultaneously, it ensures the venting of a small amount of residual gas inside the cavity of the transfer cylinder 3, preventing defects such as plastic bubbles and surface blemishes caused by localized residual gas, thus improving product molding quality. The sealing components ensure reliable sealing when the vents are closed, preventing gas leakage from affecting pressure control and further guaranteeing stable equipment operation.

[0024] As a further embodiment of the present invention, the sealing assembly includes a main exhaust channel 7 arranged in a circumferential array within the main exhaust hole 4; A sealing plug 8 that can seal the main exhaust passage 7 is slidably connected in the vertical direction inside the main exhaust port 4. A pressure spring 9 is fixedly connected to the upper surface of the piston 8. The upper end of the pressure spring 9 is fixedly connected to the inner top wall of the main exhaust port 4. The top of the main exhaust port 4 is in a sealed state. The upper end of the secondary exhaust port 6 is sealed, and a secondary exhaust channel 10 is arranged in a circumferential array on its inner wall. A sealing plug 11 that can seal the secondary exhaust channel 10 is slidably connected in the vertical direction inside the secondary exhaust port 6.

[0025] like Figure 6 As shown: When the transfer cylinder 3 is feeding and efficient exhaust is required, the main exhaust port 4 and the auxiliary exhaust port 6 open together: inside the main exhaust port 4, the cavity pressure of the transfer cylinder 3 pushes the sealing plug 8 to overcome the elastic force of the pressure spring 9 and slide upward, so that the main exhaust channel 7 of the circumferential array opens and the gas is discharged through the main exhaust channel 7. Inside the secondary exhaust port 6, the sealing plug 2 11 slides upward synchronously, opening the secondary exhaust channel 10 of the inner wall circumferential array. Gas is discharged through the secondary exhaust channel 10, and the two channels work together to improve exhaust efficiency.

[0026] like Figure 7 As shown, when the plastic pressure injected into the transfer cylinder 3 decreases and the venting demand decreases, the pressure in the cavity of the main vent 4 weakens, the pressure spring 9 recovers its deformation, and pushes the sealing plug 8 downward to block the main venting channel 7, thus closing the main vent 4. Meanwhile, the sealing plug 11 in the auxiliary vent 6 remains in the upper position, and the auxiliary venting channel 10 remains open, venting a small amount of residual gas to meet basic venting requirements. Both the main and auxiliary vents are sealed at the top to ensure that gas is only discharged through the corresponding venting channel, preventing leakage.

[0027] As a further embodiment of the present invention, the pneumatic pump 5 also includes a pressurizing component, which enables the main exhaust port 4 and the auxiliary exhaust port 6 to close synchronously when the transfer cylinder 3 stops feeding, thereby creating a sealed environment at the upper end of the transfer cylinder 3; subsequently, the pneumatic pump 5 injects high-pressure gas into the transfer cylinder 3, and applies a continuous and sufficient extrusion thrust to the molten plastic inside the cylinder through the gas pressure, thereby keeping the plastic strip extruded by the extruder 2 in a continuous molding shape; The pressurization assembly includes a pressurization chamber 12 fixedly connected to the air outlet of the pneumatic pump 5. Two air guide pipes 13 are fixedly connected to both sides of the pressurization chamber 12. The air outlets of the two air guide pipes 13 are respectively connected to the interior of the main exhaust port 4 and the auxiliary exhaust port 6. An air outlet block 14 is fixedly connected to the outlet of the air guide pipe 13 located in the auxiliary exhaust port 6. When the rotating drum 3 stops feeding, the pneumatic pump 5 can inject gas into the main exhaust port 4 and the auxiliary exhaust port 6 through the air pipes 13. The air pressure presses the sealing plug 1 8 and the sealing plug 2 11 downwards, preventing them from shifting and disengaging them from the main exhaust channel 7 and the auxiliary exhaust channel 10. The lower end of the pressurized chamber 12 is sealed with a pressure control valve 15.

[0028] like Figure 8 As shown: When the transfer drum 3 stops feeding, the pneumatic pump 5 starts its pressurization component: First, the gas generated by the air pressure pump 5 enters the pressurized chamber 12 connected to it, and then is delivered to the main exhaust port 4 and the auxiliary exhaust port 6 through the air guide pipes 13 on both sides of the pressurized chamber 12. The air guide pipe 13 in the auxiliary exhaust port 6 injects the gas evenly through the air outlet block 14. The high-pressure gas acts on the sealing plug 8 in the main exhaust port 4 and the sealing plug 11 in the auxiliary exhaust port 6, pushing them downward and pressing them tightly together. This ensures that the sealing plug 8 is completely sealed with the main exhaust channel 7 and the sealing plug 11 is completely sealed with the auxiliary exhaust channel 10. The gas pressure ensures that the sealing plugs 7 and 11 will not shift, achieving synchronous closure of the main and auxiliary exhaust ports and creating a sealed environment at the upper end of the transfer cylinder 3. Subsequently, the air pump 5 continues to inject high-pressure gas into the pressurization chamber 12. When the pressure reaches a certain value, the pressure control valve 15 opens, and the high-pressure gas is directly injected into the transfer cylinder 3 through the pressure control valve 15. Finally, the pressure at the upper end of the transfer cylinder 3 is the same as the pressure in the main exhaust port 4 and the auxiliary exhaust port 4. At this time, the internal and external pressures of the sealing plug 1 8 and the sealing plug 2 11 are consistent, and no displacement will occur. The high-pressure gas applies a continuous and sufficient extrusion thrust to the molten plastic in the cylinder, pushing the plastic stably into the extruder.

[0029] The system achieves precise linkage between sealing and pressurization in the transfer cylinder 3: On one hand, the high-pressure gas is evenly applied to sealing plugs 8 and 11 via the air guide pipe 13, ensuring that the main exhaust port 4 and the auxiliary exhaust port 6 are closed synchronously and tightly, forming a reliable sealing environment and laying the foundation for subsequent high-pressure material pushing; on the other hand, the pressure control valve 15 opens when the gas pressure reaches a certain value, making the pressure at the upper end of the transfer cylinder 13 consistent with that in the main exhaust port 4 and the auxiliary exhaust port 6. This avoids air leakage caused by displacement of sealing plugs 8 and 11 due to pressure difference, and also applies a continuous thrust to the molten plastic through stable high-pressure gas, ensuring a continuous supply of plastic to the extruder and effectively preventing plastic strip breakage. Simultaneously, the overall structure simplifies the control logic through a pressure self-balancing design, reduces additional drive components, improves the stability and reliability of equipment operation, and reduces the risk of production failures due to seal failure or pressure fluctuations. As a further embodiment of the present invention, the transfer cylinder 3 further includes a fixing rod 16 fixedly connected to its inner wall along its central axis. The fixing rod 16 is elastically slidably connected to a conical block 17 near the feed inlet of the transfer cylinder 3 by a spring. The conical block 17 is initially sealed and fitted to the feed inlet of the transfer cylinder 3.

[0030] When the transfer cylinder 3 is in its initial non-feeding state, the fixed rod 16 (fixed along the central axis of the transfer cylinder) is close to the conical block 17 connected by a spring near the feed inlet of the transfer cylinder 3. Under the action of the spring force, the conical block is tightly fitted with the feed inlet of the transfer cylinder 3, achieving an initial seal of the feed inlet and preventing external impurities from entering the transfer cylinder 3. When the purified plastic begins to feed into the transfer cylinder 3, the pressure generated by the plastic injection overcomes the spring force, pushing the conical block 17 to slide away from the feed inlet along the fixed rod 16, and the feed inlet opens accordingly, allowing the plastic to smoothly enter the interior of the transfer cylinder. When feeding stops, the pressure of the plastic on the conical block disappears, the spring returns to its original deformation, and the conical block resets, sealing the feed inlet again. The cone block 17, in conjunction with the spring, enables automatic opening and closing of the feed inlet, eliminating the need for additional drive components. This simplifies the equipment structure and control logic, while also avoiding the delay caused by manual operation of the feed inlet, thus improving feeding response efficiency. Furthermore, the initial sealing effectively isolates external dust and impurities, preventing them from entering the transfer cylinder and contaminating the molten plastic, ensuring raw material purity. The automatic reset seal after feeding stops prevents residual gas in the transfer cylinder from leaking through the feed inlet, or external air from entering and affecting the cylinder's pressure stability. This provides a good sealing foundation for subsequent pressurization and feeding by the pneumatic pump, indirectly ensuring the continuous shape of the extruded plastic strip.

[0031] As a further embodiment of the present invention, the intermediate drum 3 further includes a feed pipe 18 and a discharge pipe 19. The first and last ends of the feed pipe 18 are fixedly and sealed to the discharge port of the impurity remover 1 and the feed port of the intermediate drum 3; the first and last ends of the discharge pipe 19 and the discharge port of the intermediate drum 3 are fixedly and sealed to the feed port of the extruder 2.

[0032] As a further embodiment of the present invention, the lower end of the transfer cylinder 3 is tapered.

[0033] A gradient impurity removal method for recycled plastics, the method being as follows: S1: The melted plastic is introduced into the impurity removal machine 1 for impurity removal; S2: The plastic removed by the impurity remover 1 is introduced into the transfer cylinder 3 for transfer, so as to realize the uninterrupted conveying of the plastic to the extruder 2. The extruder 2 is equipped with a special mold for extruding the plastic into strips. S3: Extruder 2 continuously extrudes molten plastic into strips through its internal mold.

Claims

1. A gradient impurity removal mold for recycled plastics, comprising an impurity removal machine (1) and an extruder (2), characterized in that: It also includes a transfer cylinder (3) for connecting the impurity remover (1) and the extruder (2); The transfer cylinder (3) is provided with a main exhaust port (4) and an air pressure pump (5); The main exhaust port (4) can discharge the gas inside the cavity of the transfer cylinder (3) when the transfer cylinder (3) is fed; thus ensuring the product molding quality, improving production efficiency and protecting the mold and equipment. When the air pump (5) stops feeding into the intermediate drum (3), it can seal the main exhaust port (4) and inject high-pressure gas into the intermediate drum (3). The gas pressure is used to apply a continuous and sufficient extrusion thrust to the molten plastic in the intermediate drum (3), so that the plastic strip extruded by the extruder (2) maintains a continuous shape and avoids breakage.

2. The gradient impurity removal mold for recycled plastics according to claim 1, characterized in that: The transfer cylinder (3) is provided with a secondary exhaust port (6), which can be opened in conjunction with the main exhaust port (4) to improve the exhaust efficiency of the transfer cylinder (3); when the plastic pressure injected into the transfer cylinder (3) decreases and the exhaust demand decreases, the main exhaust port (4) is closed and the secondary exhaust port (6) remains open to meet the basic exhaust demand. The main exhaust port (4) and the auxiliary exhaust port (6) are equipped with sealing components.

3. The gradient impurity removal mold for recycled plastics according to claim 2, characterized in that: The sealing assembly includes a main exhaust channel (7) arranged in a circumferential array within the main exhaust port (4). The main exhaust port (4) is slidably connected in the up and down direction to a sealing plug (8) that can seal the main exhaust channel (7). A pressure spring (9) is fixedly connected to the upper surface of the piston (8). The upper end of the pressure spring (9) is fixedly connected to the inner top wall of the main exhaust port (4). The top of the main exhaust port (4) is in a sealed state. The upper end of the secondary exhaust port (6) is sealed, and a secondary exhaust channel (10) is arranged in a circumferential array on its inner wall. A sealing plug (11) that can seal the secondary exhaust channel (10) is slidably connected in the upper and lower directions inside the secondary exhaust port (6).

4. The gradient impurity removal mold for recycled plastics according to claim 3, characterized in that: The pneumatic pump (5) also includes a pressurizing component, which enables the main exhaust port (4) and the auxiliary exhaust port (6) to close synchronously when the transfer cylinder (3) stops feeding, so that a sealed environment is formed at the upper end of the transfer cylinder (3); then the pneumatic pump (5) injects high-pressure gas into the transfer cylinder (3), and applies a continuous and sufficient extrusion thrust to the molten plastic in the cylinder through the gas pressure, thereby keeping the plastic strip extruded by the extruder (2) in a continuous molding shape; The pressurization assembly includes a pressurization chamber (12) fixedly connected to the air outlet of the air pump (5). Two air guide pipes (13) are fixedly connected to both sides of the pressurization chamber (12). The air outlets of the two air guide pipes (13) are respectively connected to the interior of the main exhaust port (4) and the auxiliary exhaust port (6). An air outlet block (14) is fixedly connected to the outlet of the air guide pipe (13) located in the auxiliary exhaust port (6). When the rotating drum (3) stops feeding, the air pump (5) can inject gas into the main exhaust port (4) and the auxiliary exhaust port (6) through the air pipe (13). The air pressure will press the sealing plug one (8) and the sealing plug two (11) downwards, so that the sealing plug one (8) and the sealing plug two (11) will not be displaced and will be separated from the main exhaust channel (7) and the auxiliary exhaust channel (10). The lower end of the pressurized chamber (12) is sealed with a pressure control valve (15).

5. The gradient impurity removal mold for recycled plastics according to claim 1, characterized in that: The transfer cylinder (3) also includes a fixed rod (16) fixedly connected to its inner wall along its central axis. The fixed rod (16) is elastically slidably connected to a conical block (17) near the feed inlet of the transfer cylinder (3) by a spring. The conical block (17) is initially sealed and fitted to the feed inlet of the transfer cylinder (3).

6. The gradient impurity removal mold for recycled plastics according to claim 1, characterized in that: The intermediate drum (3) also includes a feed pipe (18) and a discharge pipe (19). The beginning and end of the feed pipe (18) are fixedly and sealed to the discharge port of the impurity remover (1) and the feed port of the intermediate drum (3); the beginning and end of the discharge pipe (19) and the discharge port of the intermediate drum (3) are fixedly and sealed to the feed port of the extruder (2).

7. A gradient impurity removal mold for recycled plastics according to claim 1, characterized in that: The lower end of the transfer cylinder (3) is conical.

8. A gradient impurity removal method for recycled plastics, applicable to the gradient impurity removal mold for recycled plastics as described in any one of claims 1-7, characterized in that: The gradient impurity removal method for recycled plastics is as follows: S1: The melted plastic is introduced into the impurity removal machine (1) for impurity removal; S2: The plastic removed by the impurity remover (1) is introduced into the transfer cylinder (3) for transfer, so as to realize the uninterrupted conveying of the plastic to the extruder (2), and the extruder (2) is equipped with a special mold for extruding the plastic into strips. S3: The extruder (2) continuously extrudes molten plastic strips outward through its internal mold.

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