A pipe extruder exhaust structure

Abstract

The application relates to the technical field of extruders, in particular to a pipeline extruder exhaust structure, which comprises a mounting frame, a vacuum pump, an outer cylinder with an opening and a threaded rod arranged in the outer cylinder, one end of the threaded rod penetrates through the outer cylinder from the end of the outer cylinder far away from the opening of the outer cylinder and is rotationally connected with the inner wall of the outer cylinder, a driven gear is fixedly connected to the outer surface of the threaded rod penetrating to the position outside the outer cylinder, the threads on the outer surface of the threaded rod abut against the inner wall of the outer cylinder, a spiral channel is formed between the outer cylinder and the threaded rod, the large diameter of the threaded rod is constant, the small diameter of the threaded rod gradually increases from the middle position to the two end positions, and the small diameter of the threaded rod far away from the opening position of the outer cylinder gradually decreases to the end surface position; the threaded rod drives the rotating ring to rotate, the rotating angle of the rotating ring is greater than the rotating angle of the threaded rod, when the threaded rod pushes the plastic melt to move, the rotating ring and the storage holes thereon can exchange the plastic melt above and below the threaded rod, and the resistance of the plastic melt to the overflow of the internal gas is reduced.

Description

Technical Field

[0001] This invention relates to the field of extruder technology, specifically to a venting structure for a pipe extruder. Background Technology

[0002] In a typical extruder, a threaded rod is placed inside a sleeve, and then plastic granules are placed inside the sleeve. The plastic granules are heated and melted by heating tubes on the threaded rod and the sleeve. The friction between the plastic granules or molten plastic and the threaded rod is less than the friction on the inner wall of the sleeve, causing the threaded rod to rotate and drive the plastic granules or molten plastic forward. However, air may be present in the plastic granules, and some plastic granules may contain volatile gases or moisture, which will form bubbles after melting. Therefore, it is necessary to remove the bubbles. Generally, the diameter of the threaded rod is gradually reduced (increasing the storage space for the molten plastic), and an vent is opened at this point in the sleeve to apply negative pressure, causing the bubbles in the molten plastic to be expelled.

[0003] However, during gas discharge, the increased storage space of the molten plastic causes the molten plastic level to drop. Since the vent is located above the threaded rod, and the molten plastic is propelled by the rotating threaded rod, the molten plastic below the threaded rod axis is only propelled by the lower part of the threaded rod. Furthermore, the upward path of the bubbles is inclined, preventing the bubbles in the lower molten plastic from completely overflowing from the surface, thus leaving bubbles in the molten plastic. Additionally, when some gas overflows from the molten plastic, it carries away a significant amount of heat, appropriately lowering the temperature. The molten plastic located between the two threads of the threaded rod and at the lower position does not directly contact the sleeve or the threaded rod surface, resulting in low thermal conductivity. This lowers the temperature at the center of the molten plastic, increasing its ability to absorb gas and moisture, further increasing the gas content in the molten plastic. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a venting structure for a pipe extruder. The structure uses an outer cylinder to drive a rotating assembly and a rotating ring to rotate. The rotating ring and its storage holes transfer the molten plastic in the lower channel of the threaded rod to the upper position, thereby increasing the rate at which gas is discharged from the molten plastic.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A venting structure for a pipe extruder includes a mounting frame, a vacuum pump, an outer cylinder with an opening, and a threaded rod disposed within the outer cylinder. One end of the threaded rod passes through the outer cylinder from the end furthest from the opening and is rotatably connected to the inner wall of the outer cylinder. A driven gear is fixedly connected to the outer surface of the threaded rod extending to the outside. The thread on the outer surface of the threaded rod abuts against the inner wall of the outer cylinder, forming a helical channel between the outer cylinder and the threaded rod. The major diameter of the threaded rod remains constant, while the minor diameter gradually increases from the middle position to both ends. Furthermore, the minor diameter of the threaded rod furthest from the outer cylinder opening gradually decreases towards the end face. The threaded rod includes a rotating shaft and three sleeves, with adjacent two... The end faces of the sleeves are fixedly connected by a rotating shaft. A rotating ring and a rotating assembly are provided between two adjacent sleeves. The rotating ring is annular and passes through the thread on the threaded rod. Several storage holes communicating with different positions of the channel are passed through the rotating ring along the axis of the outer cylinder. The outer wall of the rotating ring is rotatably connected to the inner wall of the outer cylinder. The rotating ring and the sleeve are connected by the rotating assembly. The threaded rod drives the rotating ring to rotate through the rotating assembly. The rotation angle of the rotating ring is greater than the rotation angle of the threaded rod. The outer cylinder and the vacuum pump are fixedly connected to the mounting bracket. The vacuum pump's suction pipe communicates with the inner wall of the outer cylinder, and its communication position is located at the minimum diameter position of the threaded rod. A feeding shell passes through the inner wall of the outer cylinder away from the outer cylinder opening.

[0006] By adopting the above technical solution, an external motor drives the driven gear on the threaded rod to rotate via the driving gear. The driven gear drives the threaded rod to rotate, and the threaded rod drives the rotating shaft and the second gear to rotate around the axis of the threaded rod. At the same time, the second gear meshes with the first gear and rotates around the axis of the rotating shaft. Then, the second gear meshes with the third gear and drives the rotation to rotate around the axis of the threaded rod. When the threaded rod drives the thread on it to rotate and pushes the molten plastic along the axis of the threaded rod, the molten plastic in the channel enters the storage hole. The rotating ring drives the storage hole to move from the upper position of the spiral channel to the lower position. After the transfer, the molten plastic in the storage hole is pushed out by the thread on the threaded rod, thereby exchanging the molten plastic in the upper and lower positions of the threaded channel, increasing the overflow rate of gas in the molten liquid, and improving product quality.

[0007] The present invention is further configured such that: the rotating assembly includes a first gear, a second gear, and a third gear; a support block is fixedly connected to the upper end of the mounting bracket near the protruding end face of the support shaft; a support shaft is fixedly connected to the surface of the support block, and the support shaft passes through the threaded rod and is rotatably connected; the axis of the rotating shaft is parallel to the axis of the threaded rod, and the distance between them is less than the cross-sectional radius of the sleeve; the second gear is disposed on the outer surface of the rotating shaft and is rotatably connected to the rotating shaft; the first gear is fixedly connected to the outer surface of the support shaft; the first gear is located between the two sleeves and meshes with the second gear; and the third gear is fixedly connected to the inner wall of the rotating ring and meshes with the second gear.

[0008] By adopting the above technical solution, when the motor drives the threaded rod to rotate, the second gear rotates around the axis of the threaded rod, causing the rotating ring to rotate. At the same time, the rotation of the second gear increases the rotation angle of the rotating ring relative to the threaded rod, so that when the threaded rod rotates, the rotation speed of the rotating ring is greater than the rotation speed of the threaded rod. This increases the exchange rate of the plastic melt at the upper and lower positions, further increasing the gas discharge rate. At the same time, the method of using the rotating ring to transfer the plastic melt can also prevent the gas heat from being quickly absorbed by the upper plastic melt when the bubbles move from bottom to top. It also prevents the upper plastic melt from absorbing the gas and heat of the lower melt after releasing gas, thus increasing the exhaust effect. It can also prevent splashing when the gas quickly breaks free from the liquid surface, and prevent the plastic melt from sticking to the inner wall of the exhaust shell. This prevents the plastic melt sticking to the inner wall of the exhaust shell from continuously absorbing heat and burning, as burnt plastic solids will affect product quality.

[0009] The invention is further configured such that: an annular sliding groove is formed on the inner wall of the outer cylinder; the rotating ring is slidably connected to the inner wall of the sliding groove; the width of the rotating ring is greater than the distance between two adjacent sleeves; an annular sealing groove is formed on the end faces of the sleeves that are close to each other; a sealing block is fixedly connected to the inner wall of the rotating ring; the sealing block is L-shaped and folded towards the end face of the sleeve; the sealing block is slidably connected to the inner wall of the sealing groove; and the distance between the sealing block and the axis of the outer cylinder is greater than the distance between the rotating shaft and the axis of the outer cylinder.

[0010] By adopting the above technical solution, utilizing the structure of the rotating ring slidingly connected to the inner wall of the sliding groove, and the structure of the sealing block slidingly connected to the inner wall of the sealing groove, the molten plastic passes through the storage hole and completes the propulsion of the molten plastic. At the same time, the molten plastic will not enter the space between the two adjacent sleeves and the rotating ring, ensuring the normal meshing of the first gear, the second gear and the third gear. It also allows the molten plastic above and below the threaded rod to mix, and also makes the heat uniform. It prevents the molten plastic below from still having a high temperature after the upper molten plastic releases heat, and allows for precise temperature control. When it is necessary to increase the temperature to increase the gas discharge efficiency, it prevents the molten plastic below from scorching on the inner wall of the outer cylinder and the surface of the threaded rod. This increases both the product output speed and the product quality.

[0011] The invention is further configured such that: the inner wall of the outer cylinder is permeated by an exhaust shell, and the projection of the rotating ring and the intermediate sleeve is located at the center of the projection area of ​​the inner cavity space of the exhaust shell.

[0012] By adopting the above technical solution, the projected area of ​​the inner cavity of the exhaust shell is ensured to be larger than the projected area of ​​the rotating ring and the intermediate sleeve. This allows the gas overflowing from the molten plastic at the intermediate sleeve to be discharged. At the same time, after the first transfer of molten plastic, the second transfer of molten plastic can also discharge the gas. Moreover, the time for the second release of molten plastic gas is shorter than that of the first. This ensures effective gas discharge while reducing the area of ​​the outer cylinder connected to the outside, thereby increasing the insulation effect of the outer cylinder, preventing the rapid loss of heat from the molten plastic inside the outer cylinder, and increasing energy utilization.

[0013] The present invention is further configured such that the minor diameter of the sleeve located in the middle position is smaller than the minor diameter of the sleeves located on both sides.

[0014] By adopting the above technical solution, when the plastic melt undergoes the first vertical position transfer, the volume of the channel for the movement of the plastic melt in the middle sleeve position increases, causing the liquid level of the plastic melt to drop, thereby increasing the contact area between the plastic melt and the inner cavity of the venting shell, increasing the bubble overflow rate in the plastic melt, and at the same time, using the volume change to reduce the pressure, thereby reducing the solubility of the gas, which is conducive to the generation of bubbles.

[0015] The present invention is further configured such that: an inner module is detachably connected to one end of the support shaft near the opening of the outer cylinder, and the inner module abuts against the end of the outer cylinder near the opening of the outer cylinder, and a cooling extrusion cavity is formed between the inner module and the inner wall of the outer cylinder.

[0016] By adopting the above technical solution and utilizing the detachable connection between the inner module and the support shaft, pipes with different wall thicknesses can be formed. Alternatively, molds of different shapes can be installed on the inner wall of the outer cylinder opening and then combined with the inner module to form pipe structures of different shapes. The combination of the rotating threaded rod and the stationary support shaft facilitates the replacement of the extrusion nozzle mold.

[0017] The present invention is further configured such that the thermal conductivity of the rotating ring and the sealing block is greater than 45 W / m·°C.

[0018] By adopting the above technical solution, when the rotating ring rotates, the high thermal conductivity of the rotating ring and the sealing block allows the heat from the outer surface of the threaded rod and the inner surface of the outer cylinder to be quickly transferred along the cross-sectional direction of the outer cylinder to the interior of the molten plastic. This prevents the molten plastic from losing a large amount of heat at the surface when the gas is discharged, thus avoiding uneven temperature distribution. This allows the temperature of the outer cylinder and the threaded rod to be quickly reflected in the temperature of the molten plastic, improving temperature control effectiveness, reducing the time required for temperature control, and preventing the molten plastic near the inner wall of the outer cylinder and the outer surface of the threaded rod from scorching during temperature control. It is also suitable for extrusion processes of materials with low specific heat capacity, thus improving product quality.

[0019] In summary, the present invention has the following beneficial effects:

[0020] By using a threaded rod to drive a rotating ring, and setting the rotation angle of the rotating ring to be greater than that of the threaded rod, when the threaded rod pushes the molten plastic to move, the rotating ring and its storage hole can exchange the molten plastic located above and below the threaded rod, reducing the resistance to the overflow of gas inside the molten plastic and increasing product quality.

[0021] By rotating the ring and setting its thermal conductivity, the rotating ring and storage hole can ensure that the plastic melt maintains a certain temperature at the liquid surface and internal position, before and after gas release, while driving the transfer of the plastic melt. This reduces the impact of the melt's specific heat capacity and thermal conductivity on the exhaust efficiency, increases the equipment's applicability to molten materials, and precisely controls the temperature to improve product quality.

[0022] The use of a rotating ring and storage hole to vent molten plastic increases the rate of gas discharge. At the same time, it reduces the contact area between the molten plastic surface and the inner cavity of the exhaust shell, thus reducing the contact area between the outer cylinder and the outside through the inner cavity of the exhaust shell. This reduces the heat loss rate of the outer cylinder through the exhaust shell, thereby increasing the insulation effect of the outer cylinder and increasing energy utilization. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the present invention;

[0024] Figure 2 This is a cross-sectional schematic diagram of the present invention;

[0025] Figure 3 This is a schematic diagram of the structure at point A in this invention;

[0026] Figure 4 This is a schematic diagram of the sleeve structure in this invention;

[0027] Figure 5 This is a schematic diagram of the support shaft structure in this invention;

[0028] Figure 6This is a schematic diagram of the outer cylinder in this invention;

[0029] Figure 7 This is a schematic diagram of the rotating ring in this invention.

[0030] In the picture:

[0031] 11. Mounting bracket; 12. Outer cylinder; 13. Support shaft; 14. Sleeve; 15. Rotating shaft; 16. Sealing groove; 17. First gear; 18. Second gear; 19. Third gear; 20. Sliding groove; 21. Sealing block; 22. Rotating ring; 23. Storage hole; 24. Exhaust shell; 25. Feeding shell; 26. Support block; 27. Inner module. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings of the embodiments thereof. Example

[0033] This is a type of exhaust structure for a pipe extruder, such as Figures 1 to 7As shown, the device includes a mounting bracket 11, a vacuum pump, an outer cylinder 12 with an opening, and a threaded rod disposed within the outer cylinder 12. One end of the threaded rod passes through the outer cylinder 12 away from the opening and is rotatably connected to the inner wall of the outer cylinder 12. A driven gear is fixedly connected to the outer surface of the threaded rod extending to the outside. The thread on the outer surface of the threaded rod abuts against the inner wall of the outer cylinder 12, forming a helical channel between the outer cylinder 12 and the threaded rod. The major diameter of the threaded rod remains constant, while the minor diameter gradually increases from the middle position to both ends. Furthermore, the minor diameter of the threaded rod away from the opening of the outer cylinder 12 gradually decreases towards the end face. The threaded rod includes a rotating shaft 15 and three sleeves 14. Two adjacent sleeves 14... The end faces are fixedly connected by a rotating shaft 15. A rotating ring 22 and a rotating assembly are provided between two adjacent sleeves 14. The rotating ring 22 is annular and passes through the thread on the threaded rod. Several storage holes 23 communicating with different positions of the channel are passed through the rotating ring 22 along the axis of the outer cylinder 12. The outer wall of the rotating ring 22 is rotatably connected to the inner wall of the outer cylinder 12. The rotating ring 22 and the sleeve 14 are connected by a rotating assembly. The threaded rod drives the rotating ring 22 to rotate through the rotating assembly, and the rotation angle of the rotating ring 22 is greater than the rotation angle of the threaded rod. The outer cylinder 12 and the vacuum pump are fixedly connected to the mounting bracket 11. The vacuum pump's suction pipe communicates with the inner wall of the outer cylinder 12, and its communication position is located at... At the minimum position of the threaded rod's minor diameter, a feeding shell 25 penetrates the inner wall of the outer cylinder 12, away from the opening of the outer cylinder 12. The rotating assembly includes a first gear 17, a second gear 18, and a third gear 19. A support block 26 is fixedly connected to the upper end of the mounting bracket 11 near the protruding end face of the support shaft 13. The support shaft 13 is fixedly connected to the surface of the support block 26, and the support shaft 13 passes through the threaded rod and is rotatably connected. The axis of the rotating shaft 15 is parallel to the axis of the threaded rod, and the distance between them is less than the cross-sectional radius of the sleeve 14. The second gear 18 is disposed on the outer surface of the rotating shaft 15 and is rotatably connected to the rotating shaft 15. The first gear 17 is fixedly connected to the outer surface of the support shaft 13. The first gear 17 is positioned... The second gear 18 is located between the two sleeves 14 and meshes with the third gear 19, which is fixedly connected to the inner wall of the rotating ring 22 and meshes with the second gear 18. The inner wall of the outer cylinder 12 is provided with an annular sliding groove 20, and the rotating ring 22 is slidably connected to the inner wall of the sliding groove 20. The width of the rotating ring 22 is greater than the distance between the two adjacent sleeves 14. The end faces of the sleeves 14 that are close to each other are provided with an annular sealing groove 16. A sealing block 21 is fixedly connected to the inner wall of the rotating ring 22. The sealing block 21 is L-shaped and folded towards the end face of the sleeve 14. The sealing block 21 is slidably connected to the inner wall of the sealing groove 16, and the distance between the sealing block 21 and the axis of the outer cylinder 12 is greater than the distance between the rotating shaft 15 and the axis of the outer cylinder 12.

[0034] like Figure 2 and Figure 3 As shown, the inner wall of the outer cylinder 12 is penetrated by the exhaust shell 24, and the projection of the rotating ring 22 and the intermediate sleeve 14 is located at the center of the projection area of ​​the inner cavity space of the exhaust shell 24.

[0035] like Figure 2 and Figure 4 As shown, the minor diameter of the sleeve 14 located in the middle position is smaller than the minor diameter of the sleeves 14 located on both sides.

[0036] like Figure 1 and Figure 2 As shown, an inner module 27 is detachably connected to one end of the support shaft 13 near the opening of the outer cylinder 12, and the inner module 27 abuts against the end of the outer cylinder 12 near the opening of the outer cylinder 12, forming a cooling extrusion chamber between the inner module 27 and the inner wall of the outer cylinder 12.

[0037] like Figure 3 As shown, the thermal conductivity of the rotating ring 22 and the sealing block 21 is greater than 45 W / m·°C.

[0038] Solid plastic granules are fed into the outer cylinder 12 through the opening of the feeding shell 25. At this time, the plastic granules are located in the threaded gap on the support shaft 13 inside the outer cylinder 12. Then, the power is turned on to preheat the threaded rod and the heating tube inside the outer cylinder 12. Then, the external motor is turned on, and the drive gear on the output shaft of the external motor rotates. The drive gear meshes with the driven gear on the sleeve 14 and drives the threaded rod to rotate, that is, it drives the sleeve 14, the thread on the sleeve 14, and the rotating shaft 15 to rotate around the axis of the outer cylinder 12. All three rotate relative to the support shaft 13. The support block 26 fixes the support shaft 13 and the mounting bracket 11 to the sleeve 14. When the thread on the sleeve 14 rotates, the plastic granules near the support block 26 are pushed towards the opening of the outer cylinder 12. Because the small diameter of the sleeve 14 gradually increases here, that is, the gap between the sleeve 14, the thread on the sleeve 14, and the inner wall of the outer cylinder 12 is formed. The reduced channel space allows for the application of extrusion pressure to the plastic particles, preventing a large amount of air from entering the extruder. The friction between the plastic particles and the inner wall of the outer cylinder 12 is greater than the friction between the plastic particles and the threaded rod, propelling the plastic particles forward. Simultaneously, the plastic particles are heated by the heating tubes inside the sleeve 14 and the outer cylinder 12, causing the plastic particles in the channel away from the support block 26 and close to the rotating ring 22 to gradually melt and form a molten plastic. The gradually decreasing diameter of the sleeve 14 increases the channel volume. Because the extruded plastic particles disconnect the inner cavity of the outer cylinder 12, the pressure of the molten plastic is reduced, thus reducing the solubility of residual air, volatile gases, and water vapor in the molten plastic. The vacuum pump and exhaust shell 24 further reduce the air pressure in the channel located at the exhaust shell 24, increasing the vacuum level and facilitating the discharge of gases from the molten plastic.

[0039] Simultaneously, the rotation of sleeve 14 and shaft 15 drives the second gear 18 to revolve around the axis of outer cylinder 12. The second gear 18 meshes with the first gear 17 on support shaft 13, thereby driving the second gear 18 to rotate around the axis of shaft 15. The rotation of the second gear 18 drives the third gear 19 to rotate around the axis of outer cylinder 12. The revolution and rotation of the second gear 18 drive the third gear 19 and rotating ring 22 to rotate around outer cylinder 12, thus making the rotation angle of rotating ring 22 greater than the rotation angle of sleeve 14. When the plastic granules and molten plastic are pushed by the threads on sleeve 14, the rotating ring 22 rotates relative to sleeve 14, causing the storage hole 23 on rotating ring 22 to move above and below the threaded rod. When the thread on cylinder 14 rotates, it pushes the molten plastic to move, pushing the molten plastic to the right of rotating ring 22 into storage hole 23 and pushing the molten plastic in storage hole 23 to the left of rotating ring 22. This completes the exchange of molten plastic above and below the threaded rod, transferring the molten plastic below the threaded rod to the surface of the molten plastic above. This reduces the resistance to the transfer of gas inside the molten plastic to the surface and overflow, increasing venting efficiency. At the same time, this method of transfer prevents bubbles from bursting at the surface when rising rapidly, instead causing them to burst on the inner wall of storage hole 23. This prevents molten plastic from splashing onto the inner wall of vent shell 24, preventing the molten plastic on vent shell 24 from being continuously heated, solidified, and charred, and preventing it from affecting production when it falls. The system improves product quality by utilizing the rotating ring 22 and storage hole 23 to agitate the molten plastic during heat release. This prevents heat loss from the upper molten plastic, which in turn absorbs the heat from bubbles formed in the lower molten plastic, thus preventing poor gas discharge. It also prevents the molten plastic's thermal conductivity from affecting the temperature increase at the outer cylinder 12 and threaded rod. A temperature difference is created between the inner wall of the outer cylinder 12, the outer surface of the threaded rod, and the interior of the molten plastic further away from these points, enhancing temperature control and reducing waste during startup, thus increasing economic efficiency. It also allows for the processing of materials with different specific heat capacities and thermal conductivity, expanding its application range. Furthermore, the rotating ring 22, with a thermal conductivity greater than 45 W / m·°C, and the sealing block 2... 1. To further increase the rate of heat transfer from the outer cylinder 12 and the threaded rod to the interior of the plastic, improve temperature control, and prevent uneven temperature distribution in different parts of the molten plastic after gas is released and heat is dissipated. When using materials with poor specific heat capacity, this prevents localized solidification due to excessively low temperatures or scorching due to excessively high temperatures in the molten plastic, thereby improving product quality. The materials of the rotating ring 22 and the sealing block 21 can be changed according to the thermal conductivity of different processing materials, preferably copper. The sliding connection between the rotating ring 22 and the inner wall of the sliding groove 20, the structure of the sealing block 21, and the sliding connection between the sealing block 21 and the inner wall of the sealing groove 16 ensure that the molten plastic in the channel passes through the storage hole 23, increasing work efficiency and product quality.This also prevents molten metal from entering the meshing points of the first gear 17, the second gear 18, and the third gear 19. Furthermore, this method reduces the area of ​​the outer cylinder 12 connected to the outside environment through the exhaust shell 24, thereby increasing the insulation effect of the outer cylinder 12, preventing excessive temperature loss inside the outer cylinder 12, and increasing energy utilization. The mold for the cooling nozzle is then detachably connected to the outer cylinder 12 via the inner module 27 and the support shaft 13, reducing the space occupied by the equipment. The inner wall of the outer cylinder 12 opening can also be detachably connected to a mold that mates with the inner module 27, allowing for the extrusion of tubes of different shapes.

[0040] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A venting structure for a pipe extruder, comprising a mounting frame (11), a vacuum pump, an outer cylinder (12) having an opening, and a threaded rod disposed within the outer cylinder (12), characterized in that: One end of the threaded rod passes through the outer cylinder (12) away from the opening of the outer cylinder (12) and is rotatably connected to the inner wall of the outer cylinder (12). A driven gear is fixedly connected to the outer surface of the threaded rod at the position where it passes through to the outside. The thread on the outer surface of the threaded rod abuts against the inner wall of the outer cylinder (12) and forms a spiral channel between the outer cylinder (12) and the threaded rod. The major diameter of the threaded rod remains unchanged and the minor diameter gradually increases from the middle position to both ends. The minor diameter of the threaded rod away from the opening of the outer cylinder (12) gradually decreases towards the end face. The threaded rod includes a rotating shaft (15) and three sleeves (14). The end faces of two adjacent sleeves (14) are fixedly connected by the rotating shaft (15). A rotating ring (22) and a rotating assembly are provided between two adjacent sleeves (14). The rotating ring (22) is annular and passes through the thread on the threaded rod. Several storage holes (23) communicating with different positions of the channel are passed through the rotating ring (22) along the axial direction of the outer cylinder (12). The outer wall of the rotating ring (22) is rotatably connected to the inner wall of the outer cylinder (12). The rotating ring (22) and the sleeve (14) are connected by a rotating assembly. The threaded rod drives the rotating ring (22) to rotate through the rotating assembly. The rotation angle of the rotating ring (22) is greater than the rotation angle of the threaded rod. The outer cylinder (12) and the vacuum pump are fixedly connected to the mounting bracket (11). The suction pipe on the vacuum pump is connected to the inner wall of the outer cylinder (12), and its connection position is located at the minimum position of the threaded rod. The inner wall of the outer cylinder (12) is penetrated by a feeding shell (25) at a position away from the opening of the outer cylinder (12).

2. The exhaust structure for a pipe extruder according to claim 1, characterized in that: The rotating assembly includes a first gear (17), a second gear (18), and a third gear (19). A support shaft (13) passes through the threaded rod and is rotatably connected. A support block (26) is fixedly connected to the upper end of the mounting bracket (11) near the protruding end face of the support shaft (13). The support shaft (13) is fixedly connected to the surface of the support block (26). The axis of the rotating shaft (15) is parallel to the axis of the threaded rod, and the distance between them is less than the cross-sectional radius of the sleeve (14). The second gear (18) is disposed on the outer surface of the rotating shaft (15) and is rotatably connected to the rotating shaft (15). The first gear (17) is fixedly connected to the outer surface of the support shaft (13). The first gear (17) is located between the two sleeves (14) and meshes with the second gear (18). The third gear (19) is fixedly connected to the inner wall of the rotating ring (22) and meshes with the second gear (18).

3. The exhaust structure for a pipe extruder according to claim 2, characterized in that: The inner wall of the outer cylinder (12) is provided with an annular sliding groove (20). The rotating ring (22) is slidably connected to the inner wall of the sliding groove (20), and the width of the rotating ring (22) is greater than the distance between two adjacent sleeves (14). The end faces of the sleeves (14) that are close to each other are provided with an annular sealing groove (16). A sealing block (21) is fixedly connected to the inner wall of the rotating ring (22). The sealing block (21) is L-shaped and folded towards the end face of the sleeve (14). The sealing block (21) is slidably connected to the inner wall of the sealing groove (16), and the distance between the sealing block (21) and the axis of the outer cylinder (12) is greater than the distance between the rotating shaft (15) and the axis of the outer cylinder (12).

4. The exhaust structure for a pipe extruder according to claim 3, characterized in that: The inner wall of the outer cylinder (12) is permeated by an exhaust shell (24), and the projection of the rotating ring (22) and the intermediate sleeve (14) is located at the center of the projection area of ​​the inner cavity space of the exhaust shell (24).

5. The exhaust structure for a pipe extruder according to claim 3, characterized in that: The minor diameter of the sleeve (14) located in the middle position is smaller than the minor diameter of the sleeves (14) on both sides.

6. The exhaust structure for a pipe extruder according to claim 3, characterized in that: The support shaft (13) is detachably connected to an inner module (27) at one end near the opening of the outer cylinder (12), and the inner module (27) abuts against the end of the outer cylinder (12) near the opening of the outer cylinder (12), forming a cooling extrusion cavity between the inner module (27) and the inner wall of the outer cylinder (12).

7. The exhaust structure for a pipe extruder according to claim 3, characterized in that: The thermal conductivity of the rotating ring (22) and the sealing block (21) is greater than 45 W / m·°C.

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