Environment-friendly production line of PE plastic particles

Abstract

The present application relates to the field of plastic particle production, and particularly relates to an environment-friendly production line for PE plastic particles. The present application aims to provide an environment-friendly production line for PE plastic particles, which can quickly replace and maintain the cutting tool without stopping the machine to ensure continuous production, improve production efficiency and maintenance convenience. The environment-friendly production line for PE plastic particles comprises a screw extruder, an underwater cutting device fixed to the rear side of the screw extruder, and a centrifugal dryer fixed to the rear side of the underwater cutting device. The underwater cutting device comprises a multi-channel valve, a cutting die head connected to the rear side of the multi-channel valve and provided with multiple flow channels and cutting chambers, and a cutting tool group arranged on one side of the cutting chamber of the cutting die head and used for cutting the molten material. The present application can quickly replace and maintain the cutting tool without stopping the machine to ensure continuous production, improve production efficiency and maintenance convenience.

Description

Technical Field

[0001] This invention relates to the field of plastic pellet production, and more particularly to an environmentally friendly production line for PE plastic pellets. Background Technology

[0002] Traditional waste plastic recycling extrusion granulators work by melting and filtering the plastic, extruding it into strands, and then cooling and solidifying it before pelletizing. Underwater pelletizing extrusion granulators, however, are a new type of machinery that directly pelletizes the molten plastic upon contact with cooling water at the moment of extrusion, without the need for strands or when strands are not feasible. Melt pelletizing has significant advantages over solid pelletizing. Because the plastic is scraped off by the blades in a molten state and solidified after cooling with circulating water, this pelletizing method can be used for polymers of varying viscosities. Pelleting in the molten state does not generate any dust, and the pellets are uniform in shape, making packaging and transportation more convenient. The die head's output and pelletizing speed are automatically adjusted according to the extrusion volume to change the pellet size. Alternatively, different numbers of blades can be manually used with different blade holders. This technology allows for changes in pellet size and shape; integrates pelletizing and cooling, significantly reducing floor space; automates the pelletizing process, making it easy to operate, with low noise and high-quality pellets, resulting in higher output and lower energy consumption compared to traditional strip pelletizing. However, existing underwater pelletizing production lines have high maintenance costs, and the pelletizing blades are prone to wear during use. When the blades wear down to a certain extent, the cut pellets will have some burrs. The water absorbed by these burrs is difficult to remove during subsequent dehydration, resulting in high moisture content. Therefore, it is necessary to stop the machine for replacement, causing the entire line to be interrupted. Therefore, there is an urgent need to develop an environmentally friendly production line for PE plastic pellets that allows for quick replacement and maintenance of pelletizing blades without stopping the machine, ensuring continuous production, and improving production efficiency and ease of maintenance. Summary of the Invention

[0003] In order to overcome the shortcomings of existing underwater pelletizing production lines, such as high maintenance costs and the need for downtime for replacement, which leads to the interruption of the entire line, the present invention aims to provide an environmentally friendly production line for PE plastic pellets that allows for rapid replacement and maintenance of pelletizing tools without downtime, ensuring continuous production, and improving production efficiency and ease of maintenance.

[0004] This invention is achieved through the following specific technical means:

[0005] An environmentally friendly production line for PE plastic granules includes a screw extruder; an underwater pelletizing device fixedly installed behind the screw extruder for pelletizing; and a centrifugal dryer fixedly installed behind the underwater pelletizing device for drying the plastic granules.

[0006] The underwater pelletizing device includes a multi-channel valve fixedly connected to the discharge end of the screw extruder for controlling the flow direction of the molten plastic material; a pelletizing die head connected to the rear side of the multi-channel valve and having multiple flow channels and pelletizing chambers; a pelletizing blade assembly disposed on one side of the pelletizing chamber of the pelletizing die head for pelletizing the molten material; and a conveying pipe assembly connected to the multiple pelletizing chambers of the pelletizing die head for cooling and conveying the plastic pellets.

[0007] The pelletizing die includes a first die, a second die, and a third die, which are fixedly connected in sequence. The first die has a first conveying cavity at its center, which extends through both sides and communicates with the discharge port of a multi-channel valve. The second die extends into the first conveying cavity of the first die at one end near the first die, and has a second conveying cavity at its center, which extends through both sides and communicates with the discharge port of the multi-channel valve. The first and second conveying cavities form a ring-shaped nested structure. A protruding shaft section connected to the first die is also provided on the outer surface of the second die. An annular first pelletizing cavity is provided on the end face of the protruding shaft section away from the first die, and an extrusion hole communicating with the first pelletizing cavity is provided on the annular end face of the protruding shaft section near the first die. A second pelletizing cavity is provided on the end face of the third die away from the second die, and an extrusion hole communicating with the second pelletizing cavity is provided on the annular end face of the third die.

[0008] The pelletizing blade assembly includes a first pelletizing blade assembly disposed on one side of the first pelletizing cavity of the second die head; and a second pelletizing blade assembly disposed on one side of the second pelletizing cavity of the third die head.

[0009] The conveying pipe assembly includes a water supply pipe and a drain pipe fixedly connected to opposite sides of the first pelletizing chamber; a water supply branch pipe and a drain branch pipe fixedly connected to opposite sides of the second pelletizing chamber; the other end of the water supply pipe is fixedly connected to a water tank, and the other end of the drain pipe is fixedly connected to the water inlet of the centrifugal dryer; the other end of the water supply branch pipe is fixedly connected to the water supply pipe, and the other end of the drain branch pipe is fixedly connected to the drain pipe; a first water supply valve is fixedly installed on the water supply pipe; a second water supply valve is fixedly installed on the water supply branch pipe; a first check valve is fixedly installed on the drain pipe; and a second check valve is fixedly installed on the drain branch pipe.

[0010] Furthermore, the multi-channel valve includes a valve body and a feed hole on one side of the valve body; a first feed hole and a second feed hole on the other side of the valve body, respectively connected to the feed hole; a feed annular groove connected to the first feed hole is also provided on the side of the first feed hole away from the feed hole; the second feed hole is connected to the second conveying cavity provided in the second die head; the feed annular groove is connected to the first conveying cavity provided in the first die head; a valve core is also slidably provided at the connection between the feed hole, the first feed hole and the second feed hole on the valve body; a valve stem is connected to the valve body by a nut, one end of the valve stem is connected to the valve core inside the valve body, and the other end of the valve stem extends to the outside of the valve body and is fixedly connected to a rotating wheel.

[0011] Furthermore, the first pelletizing blade assembly includes a slide block; a rotating sleeve rotatably mounted on the outer diameter surface of the slide block via a sliding sleeve; a driven pulley fixedly connected to the rotating sleeve; a housing fixedly connected to the outside of the slide block; a plurality of connecting rods extending into the first pelletizing cavity are arranged in a ring on one end face of the rotating sleeve; a first pelletizing blade is fixedly mounted on one end of the connecting rod; a first base is fixedly connected to the lower side of the housing, and the first base is provided with a mounting cavity; a first motor is fixedly connected to one side of the first base, the output shaft of the first motor extends into the mounting cavity of the first base, and a drive pulley is fixedly mounted on the output shaft of the first motor, the drive pulley being connected to the driven pulley via a synchronous belt; the first base is slidably mounted on the first base plate via a first slide rail.

[0012] Furthermore, the second pelletizing blade assembly includes a connecting cover; a second motor fixedly connected to one end face of the connecting cover; a rotating shaft rotatably mounted on the other end face of the connecting cover for extending into the second pelletizing cavity; a rotating output shaft of the second motor connected to the rotating shaft; a mounting plate fixedly mounted on one end of the rotating shaft, and a plurality of annularly arranged second pelletizing blades fixedly mounted on the mounting plate; the lower side of the connecting cover is fixedly connected to the second base via a support rod; the second base is slidably mounted on the second base plate via a second slide rail.

[0013] Furthermore, the underwater pelletizing device conveying pipe assembly also includes an air compressor tank, which is connected to the water supply pipe and the water supply branch pipe respectively through an air supply pipe; when the water supply pipe or the water supply branch pipe stops working, the air compressor tank injects high-pressure air into the pipe through the air supply pipe to quickly drain the water in the pipe.

[0014] Furthermore, the valve core has a columnar structure with conical sealing surfaces at both ends that mate with the first and second feed holes; and the height of the valve core is smaller than the diameter of the feed hole; when the upper sealing surface of the valve core mates with the second feed hole, the second feed hole is not connected to the feed hole; when the lower sealing surface of the valve core mates with the first feed hole, the first feed hole is not connected to the feed hole; when the valve core is in the middle position, both the first and second feed holes are connected to the feed hole.

[0015] Furthermore, several connecting rods are evenly distributed at equal intervals on one side end face of the rotating sleeve; this ensures that the first pelletizing blade fixedly installed on the connecting rod can cut the material at a uniform speed, ensuring that the plastic particles are of uniform size.

[0016] Furthermore, the gas supply pipe is equipped with a solenoid valve; the solenoid valve controls the opening and closing of the two gas supply pipes respectively.

[0017] Furthermore, the first and second die heads are also equipped with induction heating devices; these devices can rapidly heat the first and second die heads to prevent the molten material in the first and second conveying chambers from cooling and solidifying during maintenance of the first or second pelletizing blade assembly.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This invention achieves rapid replacement and maintenance of pelletizing blades without downtime, ensuring continuous production and improving production efficiency and ease of maintenance. By precisely controlling the valve core position, it enables flexible distribution of molten material between the central channel, outer ring channel, or both channels to meet the production needs of different specifications or outputs. It realizes independent or parallel dual extrusion channels and dual pelletizing chambers. The two sets of pelletizing blades are independently driven and controlled, and can be started, stopped, and maintained separately, perfectly matching the dual-channel design of the die head. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the main structure of the present invention.

[0021] Figure 2 This is a schematic diagram of the main structure of the underwater pelletizing device of the present invention.

[0022] Figure 3 This is a cross-sectional view of the underwater pelletizing device of the present invention.

[0023] Figure 4 This is a cross-sectional view of the pelletizing die head of the present invention.

[0024] Figure 5 This is a cross-sectional view of the first pelletizing blade assembly of the present invention.

[0025] Figure 6 This is a cross-sectional view of the second pelletizing blade assembly of the present invention.

[0026] Figure 7 This is a cross-sectional view of the multi-channel valve of the present invention.

[0027] The labels in the attached diagram are as follows: 1-Screw extruder, 2-Underwater pelletizing device, 3-Centrifugal dryer, 4-First die head, 5-Second die head, 6-Third die head, 7-Multi-channel valve, 8-First pelletizing blade assembly, 9-Second pelletizing blade assembly, 10-Water supply pipe, 11-Drainage pipe, 12-Water supply branch pipe, 13-Drainage branch pipe, 14-First water supply valve, 15-Second water supply valve, 16-First check valve, 17-Second check valve, 18-Air compressor tank, 19-Air supply pipe, 20-, 41-First conveying chamber, 51-Second conveying chamber, 52-First pelletizing chamber, 61-Second pelletizing chamber, 71-Valve body, 72-Feed 73-First feed hole, 74-Second feed hole, 75-Feeding ring groove, 76-Valve core, 77-Valve stem, 78-Rotating wheel, 81-Slide seat, 82-Rotating sleeve, 83-Slide sleeve, 84-Driven pulley, 85-Housing, 86-Connecting rod, 87-First pelletizer, 88-First base, 89-First motor, 810-Drive pulley, 811-Synchronous belt, 812-First slide rail, 813-First base plate, 91-Connecting cover, 92-Second motor, 93-Shaft, 94-Mounting plate, 95-Second pelletizer, 96-Support rod, 97-Second base, 98-Second slide rail, 99-Second base plate. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings: Example

[0029] An environmentally friendly production line for PE plastic granules, such as Figure 1-7 As shown, it includes a screw extruder 1; an underwater pelletizing device 2 fixedly disposed behind the screw extruder 1 for pelletizing; and a centrifugal dryer 3 fixedly disposed behind the underwater pelletizing device 2 for drying plastic pellets.

[0030] The underwater pelletizing device 2 includes a multi-channel valve 7 fixedly connected to the discharge end of the screw extruder 1 for controlling the flow direction of the molten plastic material; a pelletizing die head connected to the rear side of the multi-channel valve 7 and provided with multiple flow channels and pelletizing chambers; a pelletizing blade assembly disposed on one side of the pelletizing chamber of the pelletizing die head for pelletizing the molten material; and a conveying pipe assembly connected to the multiple pelletizing chambers of the pelletizing die head for cooling and conveying the plastic pellets.

[0031] The pelletizing die includes a first die 4, a second die 5, and a third die 6, which are fixedly connected in sequence. The first die 4 has a first conveying cavity 41 at its center, which extends through both sides and communicates with the discharge port of the multi-channel valve 7. The second die 5 extends into the first conveying cavity 41 at one end near the first die 4, and has a second conveying cavity 51 at its center, which extends through both sides and communicates with the discharge port of the multi-channel valve 7. The first conveying cavity 41 and the second conveying cavity 51 form a ring-shaped nested structure. The outer surface of the second die 5 also has a protruding shaft section that connects to the first die 4. The end face of the protruding shaft section away from the first die 4 has a ring-shaped first pelletizing cavity 52. ​​The end face of the protruding shaft section near the first die 4 has a ring-shaped extrusion hole that communicates with the first pelletizing cavity 52. ​​The end face of the third die 6 away from the second die 5 has a second pelletizing cavity 61. The end face of the third die 6 near the second die 5 has a ring-shaped extrusion hole that communicates with the second pelletizing cavity 61.

[0032] The pelletizing blade assembly includes a first pelletizing blade assembly 8 disposed on one side of the first pelletizing cavity 52 of the second die head 5; and a second pelletizing blade assembly 9 disposed on one side of the second pelletizing cavity 61 of the third die head 6.

[0033] The conveying pipe assembly includes a water supply pipe 10 and a drain pipe 11 fixedly connected to opposite sides of the first pelletizing chamber 52; a water supply branch pipe 12 and a drain branch pipe 13 fixedly connected to opposite sides of the second pelletizing chamber 61; the other end of the water supply pipe 10 is fixedly connected to a water tank, and the other end of the drain pipe 11 is fixedly connected to the water inlet of the centrifugal dryer 3; the other end of the water supply branch pipe 12 is fixedly connected to the water supply pipe 10, and the other end of the drain branch pipe 13 is fixedly connected to the drain pipe 11; a first water supply valve 14 is fixedly installed on the water supply pipe 10; a second water supply valve 15 is fixedly installed on the water supply branch pipe 12; a first check valve 16 is fixedly installed on the drain pipe 11; and a second check valve 17 is fixedly installed on the drain branch pipe 13.

[0034] The multi-channel valve 7 includes a valve body 71, an inlet hole 72 on one side of the valve body 71, a first feed hole 73 and a second feed hole 74 on the other side of the valve body 71, which are respectively connected to the inlet hole 72; a feed annular groove 75 connected to the first feed hole 73 is also provided on the side of the first feed hole 73 away from the inlet hole 72; the second feed hole 74 is connected to the second conveying cavity of the second die head 5; the feed annular groove 75 is connected to the first conveying cavity of the first die head 4; a valve core 76 is also slidably provided at the connection between the inlet hole 72, the first feed hole 73 and the second feed hole 74 of the valve body 71; a valve stem 77 is connected to the valve body 71 by a nut, one end of the valve stem 77 is connected to the valve core 76 inside the valve body 71, and the other end of the valve stem 77 extends to the outside of the valve body 71 and is fixedly connected to a wheel 78.

[0035] The first pelletizing blade assembly 8 includes a slide block 81; a rotating sleeve 82 rotatably mounted on the outer diameter surface of the slide block 81 via a sliding sleeve 83; a driven pulley 84 fixedly connected to the rotating sleeve 82; a housing 85 fixedly connected to the outside of the slide block 81; a plurality of connecting rods 86 for extending into the first pelletizing cavity are arranged in a ring on one end face of the rotating sleeve 82; a first pelletizing blade 87 is fixedly mounted on one end of the connecting rod 86; a first base 88 is fixedly connected to the lower side of the housing 85, and the first base 88 is provided with a mounting cavity; a first motor 89 is fixedly connected to one side of the first base 88, the rotation output shaft of the first motor 89 extends into the mounting cavity of the first base 88, and a driving pulley 810 is fixedly mounted on the rotation output shaft of the first motor 89, the driving pulley 810 being connected to the driven pulley 84 via a synchronous belt 811; the first base 88 is slidably mounted on the first base plate 813 via a first slide rail 812.

[0036] The second pelletizing blade assembly 9 includes a connecting cover 91; a second motor 92 fixedly connected to one end face of the connecting cover 91; a rotating shaft 93 rotatably mounted on the other end face of the connecting cover 91 for extending into the second pelletizing cavity 61; the rotation output shaft of the second motor 92 is connected to the rotating shaft 93; a mounting plate 94 is fixedly mounted on one end of the rotating shaft 93, and a plurality of annularly arranged second pelletizing blades 95 are fixedly mounted on the mounting plate 94; the lower side of the connecting cover 91 is fixedly connected to the second base 97 via a support rod 96; the second base 97 is slidably mounted on the second base plate 99 via a second slide rail 98.

[0037] Working principle:

[0038] Example 1:

[0039] After the PE raw material is melted and plasticized by the screw extruder 1, it enters the feed hole 72 of the multi-channel valve 7. At this time, the operating wheel 78 causes the valve stem 77 to drive the valve core 76 to the middle position. The upper and lower sealing surfaces of the columnar structure of the valve core 76 do not completely block the first feed hole 73 and the second feed hole 74. Therefore, the molten plastic passes through the first feed hole 73 and the second feed hole 74 at the same time.

[0040] The molten material passing through the first feeding hole 73 and the feeding ring groove 75 enters the annular first feeding chamber 41 of the first die head 4. The molten material in the first feeding chamber 41 flows through the extrusion hole on the side of the protruding shaft section of the second die head 5 and is extruded into the first pelletizing chamber 52. The molten material passing through the second feeding hole 74 enters the second feeding chamber 51 of the second die head 5. The molten material in the second feeding chamber 51 flows through the extrusion hole of the third die head 6 and is extruded into the second pelletizing chamber 61.

[0041] The first motor 89 starts, driving the driven pulley 84 and the rotating sleeve 82 to rotate via the driving pulley 810 and the synchronous belt 811. The connecting rod 86 on the rotating sleeve 82 drives the first pelletizing blade 87 to rotate at high speed, pelletizing the plastic strips extruded from the first pelletizing chamber 52. The second motor 92 starts, driving the rotating shaft 93 and the mounting plate 94 to rotate, driving the second pelletizing blade 95 to rotate at high speed, pelletizing the plastic strips extruded from the second pelletizing chamber 61.

[0042] The water tank of the centrifugal dryer 3 serves as the water source. The first water supply valve 14 and the second water supply valve 15 are opened simultaneously, and the water flows into the first pelletizing chamber 52 through the water supply pipe 10, and into the second pelletizing chamber 61 through the water supply branch pipe 12. The water flow immediately surrounds and cools the freshly cut hot plastic pellets in the pelletizing chamber, while carrying the pellets forward. The water in the first pelletizing chamber 52 flows to the inlet of the centrifugal dryer 3 through the drain pipe 11, and the water in the second pelletizing chamber 61 flows to the drain pipe 11 through the drain branch pipe 13. After merging, they enter the inlet of the centrifugal dryer 3 together. The water forms a closed loop between the pelletizing device and the centrifugal dryer 3. The centrifugal dryer 3 is responsible for separating the water from the pellets and reusing it, which reflects environmental protection and energy saving. The water carrying the pellets enters the centrifugal dryer 3. The dryer uses centrifugal force to separate the water from the surface of the plastic pellets. The dried PE pellets are discharged, and the separated water is circulated back to the pelletizing device as cooling water. The first pelletizing blade group 8 and the second pelletizing blade group 9 work simultaneously to ensure working efficiency.

[0043] Example 2:

[0044] When the second pelletizing blade 95 on the second pelletizing blade assembly 9 suffers significant wear after prolonged use and requires repair or replacement, the rotating wheel 78 causes the valve stem 77 to move the valve core 76 upward. At this time, the upper conical sealing surface of the valve core 76 tightly engages with the second feed hole 74, closing it. The lower conical sealing surface of the valve core 76 leaves the first feed hole 73, and the molten material can only flow out through the first feed hole 73 and the feed ring groove 75. The molten material enters the first conveying chamber 41 of the first die head 4 through the first feed hole 73 and the feed ring groove 75, and then flows through the extrusion hole on the side of the protruding shaft section of the second die head 5, and is extruded into the first pelletizing chamber 52. The first motor 89 drives the first pelletizing blade 87 to work, pelletizing the plastic strip extruded from the first pelletizing chamber 52.

[0045] When there is no material flow in the second conveying chamber 51 and the second pelletizing chamber 61, the second motor 92 stops, the second pelletizing blade assembly 9 is in a non-working state, and then the second water supply valve 15 closes, cutting off the water supply branch pipe 12 flowing to the second pelletizing chamber 61; after closing the second water supply valve 15, the air compressor tank 18 is started, the solenoid valve connecting the water supply branch pipe 12 is opened, and high-pressure air is injected into the water supply branch pipe 12 and the first pelletizing chamber 52, quickly draining the residual water through the drain branch pipe 13; then the second pelletizing blade assembly 9 is separated from the third die head 6, and the second pelletizing blade 95 on the second pelletizing blade assembly 9 is repaired and replaced.

[0046] Example 3:

[0047] When the first pelletizing blade 87 on the first pelletizing blade assembly 8 is worn after a long period of use and needs to be repaired or replaced, the rotating wheel 78 is operated to make the valve stem 77 move the valve core 76 downward. At this time, the conical sealing surface at the lower end of the valve core 76 is tightly fitted with the first feed hole 73 to close it. The conical sealing surface at the upper end of the valve core 76 leaves the second feed hole 74, and the molten material can only flow out through the second feed hole 74. The molten material enters the second conveying chamber 51 of the second die head 5 through the second feed hole 74, and then flows through the extrusion hole of the third die head 6 and is extruded into the second pelletizing chamber 61. The second motor 92 drives the second pelletizing blade 95 to work and pelletize the plastic strip extruded from the second pelletizing chamber 61.

[0048] When there is no material flow in the first conveying chamber 41 and the first pelletizing chamber 52, the first motor 89 stops, the first pelletizing blade assembly 8 is in a non-working state, and then the first water supply valve 14 is closed, cutting off the water supply pipe 10 flowing to the first pelletizing chamber 52; after closing the first water supply valve 14, the air compressor tank 18 is started, the solenoid valve connected to the water supply pipe 10 is opened, and high-pressure air is injected into the water supply pipe 10 and the first pelletizing chamber 52, quickly draining the residual water through the drain pipe 11; then the first pelletizing blade assembly 8 is separated from the second die head 5, and the first pelletizing blade 87 on the first pelletizing blade assembly 8 is repaired and replaced.

[0049] The control method of this invention is automatic control through a controller. The control circuit of the controller can be implemented by simple programming by those skilled in the art. The power supply is also common knowledge in the art. Furthermore, since this invention is mainly used to protect mechanical devices, the control method and circuit connection will not be explained in detail here.

[0050] Although this disclosure has been described in detail with reference to exemplary embodiments, it is not limited thereto, and it will be apparent to those skilled in the art that various modifications and changes may be made thereto without departing from the scope of this disclosure.

Claims

1. An environmentally friendly production line for PE plastic granules, comprising a screw extruder (1); an underwater pelletizing device (2) fixedly disposed on the rear side of the screw extruder (1) for pelletizing; and a centrifugal dryer (3) fixedly disposed on the rear side of the underwater pelletizing device (2) for drying the plastic granules. Its features are, The underwater pelletizing device (2) includes a multi-channel valve (7) fixedly connected to the discharge end of the screw extruder (1) for controlling the flow direction of the molten plastic material; a pelletizing die head connected to the rear side of the multi-channel valve (7) and provided with multiple flow channels and pelletizing chambers; a pelletizing blade assembly set on one side of the pelletizing chamber of the pelletizing die head for pelletizing the molten material; and a conveying pipe assembly connected to the multiple pelletizing chambers of the pelletizing die head for cooling and conveying the plastic particles. The pelletizing die includes a first die (4), a second die (5), and a third die (6) that are fixedly connected in sequence. The first die (4) has a first conveying chamber (41) that extends through both sides and communicates with the discharge port of the multi-channel valve (7) at its center. The second die (5) extends into the first conveying chamber (41) of the first die (4) at one end near the first die (4), and has a second conveying chamber (51) that extends through both sides and communicates with the discharge port of the multi-channel valve (7) at its center. The first conveying chamber (41) and the second conveying chamber (51) form a ring-shaped nested structure. The second die (5) has a protruding shaft section on its outer surface that is connected to the first die (4). The protruding shaft section has an annular first pelletizing cavity (52) on the side away from the first die (4). The protruding shaft section has an extrusion hole that communicates with the first pelletizing cavity (52) on the side closer to the first die (4). The third die (6) has a second pelletizing cavity (61) on the side away from the second die (5). The third die (6) has an extrusion hole that communicates with the second pelletizing cavity (61) on the side closer to the second die (5). The pelletizing blade assembly includes a first pelletizing blade assembly (8) disposed on one side of the first pelletizing cavity (52) provided in the second die head (5); and a second pelletizing blade assembly (9) disposed on one side of the second pelletizing cavity (61) provided in the third die head (6). The conveying pipe assembly includes a water supply pipe (10) and a drain pipe (11) fixedly connected to opposite sides of the first pelletizing chamber (52); a water supply branch pipe (12) and a drain branch pipe (13) fixedly connected to opposite sides of the second pelletizing chamber (61); the other end of the water supply pipe (10) is fixedly connected to a water tank, and the other end of the drain pipe (11) is fixedly connected to the inlet of the centrifugal dryer (3); the other end of the water supply branch pipe (12) is fixedly connected to the water supply pipe (10), and the other end of the drain branch pipe (13) is fixedly connected to the drain pipe (11); a first water supply valve (14) is fixedly installed on the water supply pipe (10); a second water supply valve (15) is fixedly installed on the water supply branch pipe (12); a first check valve (16) is fixedly installed on the drain pipe (11); and a second check valve (17) is fixedly installed on the drain branch pipe (13). The multi-channel valve (7) includes a valve body (71) and a feed hole (72) on one side of the valve body (71); a first feed hole (73) and a second feed hole (74) on the other side of the valve body (71) respectively connected to the feed hole (72); a feed annular groove (75) connected to the first feed hole (73) is also provided on the side of the first feed hole (73) away from the feed hole (72); the second feed hole (74) is connected to the second conveying cavity (51) provided in the second die head (5); The material conveying ring groove (75) is connected to the first conveying cavity (41) provided in the first die head (4); a valve core (76) is also slidably provided at the connection between the feed hole (72), the first material conveying hole (73) and the second material conveying hole (74) provided in the valve body (71); a valve stem (77) is connected to the valve body (71) by a nut engagement, one end of the valve stem (77) is connected to the valve core (76) inside the valve body (71), and the other end of the valve stem (77) extends to the outside of the valve body (71) and is fixedly connected to a rotating wheel (78); The first pelletizing blade assembly (8) includes a slide block (81); a rotating sleeve (82) rotatably mounted on the outer diameter surface of the slide block (81) via a sliding sleeve (83); a driven pulley (84) fixedly connected to the rotating sleeve (82); a housing (85) fixedly connected to the outside of the slide block (81); a plurality of connecting rods (86) for extending into the first pelletizing chamber are arranged in a ring on one end face of the rotating sleeve (82); a first pelletizing blade (87) is fixedly mounted on one end of the connecting rod (86); a second pelletizing blade (87) is fixedly connected to the lower side of the housing (85). A base (88) is provided with a mounting cavity; a first motor (89) is fixedly connected to one side of the first base (88), the output shaft of the first motor (89) extends into the mounting cavity provided in the first base (88), and a drive pulley (810) is fixedly installed on the output shaft of the first motor (89), the drive pulley (810) is connected to the driven pulley (84) through a synchronous belt (811); the first base (88) is slidably mounted on the first base plate (813) through a first slide rail (812); The second pelletizing blade assembly (9) includes a connecting cover (91); a second motor (92) fixedly connected to one end face of the connecting cover (91); and a rotating shaft (93) rotatably mounted on the other end face of the connecting cover (91) for extending into the second pelletizing cavity (61); the output shaft of the second motor (92) is connected to the rotating shaft (93); a mounting plate (94) is fixedly mounted on one end of the rotating shaft (93), and several annularly arranged second pelletizing blades (95) are fixedly mounted on the mounting plate (94); the lower side of the connecting cover (91) is fixedly connected to the second base (97) through a support rod (96); the second base (97) is slidably mounted on the second base plate (99) through a second slide rail (98); The underwater pelletizing device (2) also includes an air compressor tank (18), which is connected to the water supply pipe (10) and the water supply branch pipe (12) respectively through the air supply pipe (19); The valve core (76) has a columnar structure, with tapered sealing surfaces at both ends that cooperate with the first feed hole (73) and the second feed hole (74); and the height of the valve core (76) is smaller than the diameter of the feed hole (72); Several connecting rods (86) are evenly distributed at equal intervals on one side end face of the rotating sleeve (82). The gas pipeline (19) is equipped with a solenoid valve; the solenoid valve controls the opening and closing of the two gas pipelines (19) respectively; The first mold head (4) and the second mold head (5) are also equipped with an induction heating device.

Images