A meltblown mechanism for meltblown microfiber

Abstract

A meltblown mechanism for meltblown microfiber, relating to the field of meltblown mechanism technology, includes a spinneret, with a drafting assembly and a screw extruder respectively on its left and right sides. A cleaning assembly is located at the top of the spinneret, and a horizontally arranged feed tube runs through its end. One end of the feed tube is connected to the discharge end of the screw extruder. The end of the spinneret also has a nozzle that rotates horizontally. When the nozzle rotates downwards, its two ports are connected to the feed tube and the drafting assembly. The drafting assembly improves the fiber opening rate of the polymer melt, and when the nozzle rotates upwards, the cleaning assembly quickly cleans the polymer melt residue inside the nozzle. This invention solves the problems of low polymer melt opening rate and poor fiber separation in existing meltblown mechanisms for microfiber, which affect product quality; and the cumbersome and wasteful process of discharging all remaining material during shutdowns or long-term downtime.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of melt-blowing mechanisms, in particular to a melt-blowing mechanism for melt-blowing superfine fibers. BACKGROUND

[0002] The melt-blowing method is a common and cost-effective method for directly producing microfiber structures of non-woven fabrics by using polymers. The melt-blowing non-woven fabric has excellent filtering, shielding, thermal insulation and oil absorption properties, and is widely used in medical, thermal, filtering, adsorption and sound insulation fields. Two polymers are usually used when the melt-blowing method is used to manufacture non-woven fabrics. The double-component composite fibers produced by melt-mixing of the two polymers have good air permeability, strong anti-pollution ability, moisture absorption and other excellent properties.

[0003] The prior art discloses a patent with the publication number CN113265712B. The scheme includes a melt-blowing die head, a spinning hole and a gas jet hole are arranged in the melt-blowing die head, the spinning hole is used for spraying fiber polymer, the gas jet hole is used for spraying high-temperature gas to draw the high polymer sprayed from the spinning hole; a mounting assembly, the mounting assembly includes a fixed rod and a sliding block, a sliding port is arranged in the middle of the fixed rod, the sliding block is slidably arranged in the sliding port, the melt-blowing die head is fixedly arranged below the sliding block through a connecting rod; a driving assembly, the driving assembly is used for driving the sliding block to reciprocally slide in the sliding port.

[0004] The prior art including the above patent gradually exposes the deficiencies with use, mainly in the following aspects:

[0005] First, the polymer melt fiberization rate is low, the degree of fiber separation is poor, which leads to large average fiber diameter, affecting the air permeability and softness of the product. Specifically, during the production of melt-blowing superfine fibers, the melt-blowing die head sprays polymer melt and gas to the receiving screen at the same time. The gas forms a negative pressure during flow, and then draws the polymer melt to form a melt-blowing fiber web. Therefore, the higher the gas flow rate, the higher the polymer melt fiberization rate. However, the air compressor provided in the production workshop produces gas with a small wind speed, resulting in a low polymer melt fiberization rate.

[0006] Secondly, when the machine is stopped or stopped for a long time, the remaining material in the screw extruder needs to be discharged completely. The discharge process is complicated and causes material waste. Specifically, if there is material in the screw extruder, polymer melt will remain in the melt-blowing nozzle. After drying and solidification, the melt-blowing pipeline is easily blocked, which leads to the need to disassemble the melt-blowing nozzle and clean the high polymer inside the nozzle during the next production start.

[0007] In summary, the prior art has obvious inconvenience and defects in practical use, and it is necessary to improve. SUMMARY

[0008] In view of the defects in the prior art, the technical problem to be solved by the present application is to provide a melt-blowing mechanism for melt-blowing ultra-fine fibers, which can generate high-speed stretching gas, thereby improving the opening rate of polymer melt.

[0009] The melt-blowing mechanism can also quickly clean the residual polymer melt in the melt-blowing nozzle without emptying the material in the screw extruder, effectively preventing the melt-blowing nozzle from being blocked.

[0010] To solve the above problems, the present application provides the following technical solutions:

[0011] A melt-blowing mechanism for melt-blowing ultra-fine fibers, comprising a spinneret, the left and right sides of the spinneret are respectively provided with a stretching assembly and a screw extruder, the top of the spinneret is provided with a cleaning assembly, the end of the spinneret is provided with a horizontally arranged material pipe, one end of the material pipe is in communication with the discharge end of the screw extruder, the end of the spinneret is also provided with a nozzle rotating along the horizontal line, when the nozzle rotates to the lower side, its two ports are in communication with the material pipe and the stretching assembly, the stretching assembly can improve the opening rate of the polymer melt, when the nozzle rotates to the upper side, the cleaning assembly can quickly clean the residual polymer melt in the nozzle;

[0012] The stretching assembly comprises a horizontally sliding Laval nozzle, the outer wall of the gas inlet end of the Laval nozzle is uniformly distributed with a plurality of jet pipes along the circumference, one end of the jet pipe extends into the Laval nozzle, a plurality of jet pipes are connected in communication through a cold gas pipe, the gas inlet of the cold gas pipe is connected in communication with an external cold gas source,

[0013] The inner wall of the gas inlet end of the Laval nozzle is sealingly connected with a sealing ring, when the nozzle rotates to the lower side, the Laval nozzle is coaxial with the nozzle, when the Laval nozzle slides towards the nozzle, the discharge end of the nozzle can pass through the sealing ring and enter the inside of the Laval nozzle, and the outer wall of the nozzle abuts against the sealing ring;

[0014] The gas jetted out of the jet pipe greatly increases in flow rate after passing through the throat of the Laval nozzle, and the polymer melt jetted out of the nozzle is stretched by the high-speed airflow after passing through the throat of the Laval nozzle.

[0015] As an optimized scheme, the lateral side of the Laval nozzle is provided with a fixed box, a conical cover is horizontally fixed in the fixed box, opposite ports of the conical cover correspondingly extend to the outside through the fixed box, the small-diameter end of the conical cover is coaxially fixed to the exhaust end of the Laval nozzle, a plurality of through holes are uniformly distributed on the outer wall of the conical cover in the fixed box along the circumferential direction, the diameters of the through holes gradually increase along the axial direction, and the diameter of the through hole close to the Laval nozzle is the smallest,

[0016] The end of the fixed box is fixedly provided with four suction pipes which are connected with the inner cavities of the fixed box at the positions of the four corners, the four suction pipes are connected through a ventilation pipe, one end of the ventilation pipe is connected with an external negative pressure fan, and the fibers formed after being drawn pass through the conical cover and are diffused inwards in all directions under the suction of the negative pressure gas, so that the fibers are more uniformly sprayed to the receiving screen.

[0017] As an optimized scheme, the cleaning assembly comprises a positioning pipe which is horizontally fixed on the top of the spinneret, the inner diameter of the positioning pipe is equal to the inner diameter of the feed end of the nozzle, a cleaning column which is frictionally abuts against the inner wall of the positioning pipe is horizontally slidably arranged in the positioning pipe, one end of the cleaning column is in a conical structure, an exhaust passage is penetratingly arranged in the cleaning column, the exhaust port of the exhaust passage is coaxially arranged with the cleaning column, and an air inlet pipe is fixedly connected with the air inlet port of the exhaust passage.

[0018] When the nozzle is rotated to the upper side, the nozzle is coaxial with the positioning pipe, the feed end of the nozzle is connected with the positioning pipe, when the cleaning column slides to the direction close to the nozzle, the cleaning column cleans the residual material in the nozzle, when the cleaning column horizontally slides to the conical end which abuts against the nozzle, the exhaust port of the exhaust passage is connected with the spinneret hole of the nozzle, and the gas in the exhaust passage cleans the residual material in the spinneret hole.

[0019] As an optimized scheme, the end of the spinneret is rotationally provided with a circular plate which frictionally abuts against the end surface of the spinneret along a horizontal line, the nozzle is penetratingly arranged at the end of the circular plate, the feed end of the nozzle frictionally abuts against the end surface of the spinneret, the end of the circular plate is provided with a circular groove, a sealing gasket is fixedly arranged in the circular groove, and when the nozzle is rotated to be coaxial with the positioning pipe, the sealing gasket abuts against the port of the material pipe.

[0020] As an optimized scheme, the top of the spinneret is provided with two oppositely arranged arc-shaped plates which are symmetrically arranged along the axial section of the positioning pipe, the two arc-shaped plates are fixedly connected with the positioning pipe, and the nozzle and the sealing gasket can frictionally abut against the two arc-shaped plates in the rotation process of the circular plate.

[0021] As an optimized scheme, the spinneret is internally fixed with a plurality of electric heating wires, the plurality of electric heating wires are distributed on both sides of the material pipe, and the electric heating wires can heat the polymer melt in the material pipe to prevent solidification.

[0022] As an optimized scheme, the side of the spinneret is detachably provided with a collecting box with an open top, and when the nozzle is rotated upward, the spinneret orifice of the nozzle is located above the collecting box.

[0023] As an optimized scheme, the bottom of the spinneret is horizontally slidably provided with a sliding plate, one end of the sliding plate extends to the outside of the spinneret, and a vertically arranged positioning plate is fixedly connected to the end of the sliding plate, and the Laval nozzle is fixedly inserted into the positioning plate.

[0024] As an optimized scheme, a tooth ring is fixedly sleeved on the outer wall of the circular plate, a limiting plate is fixedly arranged at the end of the spinneret, and a gear meshing with the tooth ring is rotatably arranged at the end of the limiting plate along a horizontal line.

[0025] As an optimized scheme, the circular plate is rotatably connected to the spinneret through a rotating shaft, a guide column is fixedly connected to the end of the circular plate, a guide groove is arranged at the end of the spinneret, one end of the guide column extends into the guide groove, and the rotation range of the circular plate is limited by the guide groove and the guide column.

[0026] Compared with the prior art, the beneficial effects of the present application are:

[0027] 1. The drafting assembly can greatly improve the flow rate of the drafting gas, thereby improving the polymer melt opening rate, and the fibers after opening can also be uniformly diffused to the four directions.

[0028] 2. The cleaning assembly can quickly clean the residual polymer melt in the nozzle without emptying the material in the screw extruder, effectively preventing the nozzle from being blocked. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the specific embodiments or prior art description will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual scale.

[0030] Figure 1 is a structural schematic view of the present application;

[0031] Figure 2 is a structural schematic view of the Laval nozzle of the present application;

[0032] Figure 3 is a structural schematic view of the spinneret of the present application;

[0033] Figure 4 Structure diagram of fixed box of the present application;

[0034] Figure 5 Structure diagram of conical cover of the present application;

[0035] Figure 6 Structure diagram of cleaning column of the present application;

[0036] Figure 7 Structure diagram of guide groove of the present application;

[0037] Figure 8 Structure diagram of guide column of the present application.

[0038] In the figure: 1-screw extruder; 2-cleaning assembly; 3-drawing assembly; 4-nozzle; 5-spinning plate; 6-material pipe; 7-electric heating wire; 8-cold air pipe; 9-first telescopic cylinder; 10-fixed plate; 11-sliding plate; 12-positioning plate; 13-spinning hole; 14-throat; 15-laval nozzle; 16-air injection pipe; 17-sealing ring; 18-circular plate; 19-circular groove; 20-sealing gasket; 21-cleaning column; 22-conical cover; 23-through hole; 24-ventilation pipe; 25-air suction pipe; 26-fixed box; 27-tooth ring; 28-guide column; 29-rotation shaft; 30-driving motor; 31-limiting plate; 32-gear; 33-guide groove; 34-arc plate; 35-fixed support; 36-collection box; 37-exhaust passage; 38-positioning pipe; 39-air inlet pipe; 40-second telescopic cylinder; 41-supporting plate. DETAILED DESCRIPTION

[0039] The embodiments of the technical solutions of the present application will be described in detail below in combination with the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0040] As Figures 1 to 8 shown, a melt-blowing mechanism for melt-blowing ultrafine fibers comprises a spinning plate 5, the left and right sides of the spinning plate 5 are respectively provided with a drawing assembly 3 and a screw extruder 1, the top of the spinning plate 5 is provided with a cleaning assembly 2, the end of the spinning plate 5 is provided with a horizontally arranged material pipe 6, one end of the material pipe 6 is in communication with the discharge end of the screw extruder 1, the end of the spinning plate 5 is also provided with a nozzle 4 rotating along the horizontal line, when the nozzle 4 rotates to the lower side, the two ports of the nozzle 4 correspondingly communicate with the material pipe 6 and the drawing assembly 3, the drawing assembly 3 can improve the fiberizing rate of the polymer melt, when the nozzle 4 rotates to the upper side, the cleaning assembly 2 can quickly clean the residual polymer melt inside the nozzle 4;

[0041] The drawing assembly 3 comprises a horizontally sliding Laval nozzle 15, and a plurality of air injection pipes 16 are uniformly distributed on the outer wall of the air inlet end of the Laval nozzle 15 and extend into the Laval nozzle 15, the air injection pipes 16 are connected by a cold gas pipe 8, the air inlet of the cold gas pipe 8 is connected with an external cold gas source,

[0042] The inner wall of the air inlet end of the Laval nozzle 15 is sealingly connected with a sealing ring 17, when the nozzle 4 is rotated to the lower side, the Laval nozzle 15 is coaxial with the nozzle 4, when the Laval nozzle 15 slides towards the nozzle 4, the discharge end of the nozzle 4 can pass through the sealing ring 17 and enter the inside of the Laval nozzle 15, and the outer wall of the nozzle 4 abuts against the sealing ring 17;

[0043] The gas injected into the air injection pipes 16 has a greatly increased flow rate after passing through the throat 14 of the Laval nozzle 15, and the high polymer melt injected from the nozzle 4 is drawn by the high-speed airflow after passing through the throat 14 of the Laval nozzle 15.

[0044] The Laval nozzle 15 is provided with a fixing box 26, a conical cover 22 is horizontally fixed in the fixing box 26, opposite ports of the conical cover 22 extend to the outside through the fixing box 26, the small-diameter end of the conical cover 22 is coaxially fixed with the discharge end of the Laval nozzle 15, a plurality of through holes 23 are uniformly distributed on the outer wall of the conical cover 22 in the fixing box 26, the diameters of the through holes 23 gradually increase along the axial direction, the diameter of the through hole 23 close to the Laval nozzle 15 is the smallest,

[0045] The end of the fixing box 26 is fixedly provided with a suction pipe 25 connected with the inner cavity of the fixing box 26 at a four-cornered position, the four suction pipes 25 are connected by an air pipe 24, one end of the air pipe 24 is connected with an external negative pressure fan, and the fibers formed after being drawn pass through the conical cover 22 and are diffused inwards under the suction of the negative pressure gas, so that the fibers are more uniformly sprayed to the receiving curtain.

[0046] The cleaning assembly 2 comprises a positioning pipe 38 fixedly arranged on the top of the spinneret plate 5, the inner diameter of the positioning pipe 38 is equal to the inner diameter of the feeding end of the nozzle 4, a cleaning column 21 frictionally abutting against the inner wall of the positioning pipe 38 is slidingly arranged in the positioning pipe 38, one end of the cleaning column 21 is conical, an exhaust passage 37 is penetratingly arranged in the cleaning column 21, the exhaust port of the exhaust passage 37 is coaxially arranged with the cleaning column 21, the air inlet of the exhaust passage 37 is fixedly connected with an air inlet pipe 39, and the air inlet pipe 39 is connected with an external gas source;

[0047] When the nozzle 4 rotates to the upper side, the nozzle 4 is coaxial with the positioning tube 38, and the feeding end of the nozzle 4 communicates with the positioning tube 38. When the cleaning column 21 slides to the direction close to the nozzle 4, the cleaning column 21 cleans the residual material in the nozzle 4. When the cleaning column 21 horizontally slides to the position where the tapered end of the cleaning column 21 abuts against the nozzle 4, the exhaust port of the exhaust channel 37 communicates with the spinneret hole 13 of the nozzle 4. The gas in the exhaust channel 37 cleans the residual material in the spinneret hole 13.

[0048] The end of the spinneret plate 5 is provided with a circular plate 18 frictionally abutting against the end surface of the spinneret plate 5 along the horizontal line. The nozzle 4 penetrates the end of the circular plate 18. The feeding end of the nozzle 4 frictionally abuts against the end surface of the spinneret plate 5. The end of the circular plate 18 is provided with a circular groove 19. The circular groove 19 is fixedly provided with a sealing gasket 20. When the nozzle 4 rotates to be coaxial with the positioning tube 38, the sealing gasket 20 abuts against the port of the material tube 6. The diameter of the sealing gasket 20 is greater than the inner diameter of the material tube 6. The sealing gasket 20 is made of high-temperature resistant material.

[0049] The top of the spinneret plate 5 is provided with two arc-shaped plates 34 symmetrically arranged along the axial section of the positioning tube 38. The two arc-shaped plates 34 are fixedly connected with the positioning tube 38. The nozzle 4 and the sealing gasket 20 frictionally abut against the two arc-shaped plates 34 during the rotation of the circular plate 18.

[0050] A plurality of electric heating wires 7 are fixedly arranged in the spinneret plate 5. The electric heating wires 7 are distributed on both sides of the material tube 6. The electric heating wires 7 can heat the high polymer melt in the material tube 6 to prevent solidification.

[0051] The spinneret plate 5 is detachably provided with a collection box 36 with an open top. When the nozzle 4 rotates to the upper side, the spinneret hole 13 of the nozzle 4 is located above the collection box 36.

[0052] The end of the spinneret plate 5 is fixedly connected with a fixed support 35. The collection box 36 is detachably arranged on the fixed support 35.

[0053] The bottom of the spinneret plate 5 is horizontally slidably provided with a sliding plate 11. One end of the sliding plate 11 extends to the outside of the spinneret plate 5 and is fixedly connected with a vertical positioning plate 12. The Laval nozzle 15 is fixedly inserted into the positioning plate 12.

[0054] The other end of the sliding plate 11 is fixedly connected with a fixed plate 10. The bottom of the spinneret plate 5 is fixedly provided with two horizontally arranged first telescopic cylinders 9. The telescopic ends of the two first telescopic cylinders 9 are fixedly connected with the fixed plate 10.

[0055] The top of the spinneret plate 5 is fixedly connected with a support plate 41. The support plate 41 is fixedly inserted with a horizontally arranged second telescopic cylinder 40. The cleaning column 21 extends to the outside of the positioning tube 38 and is fixedly connected with the telescopic end of the second telescopic cylinder 40.

[0056] The outer wall of the circular plate 18 is fixedly sleeved with a gear ring 27, and the end of the spinneret 5 is fixedly provided with a limiting plate 31, and the end of the limiting plate 31 is rotationally provided with a gear 32 engaged with the gear ring 27 along a horizontal line.

[0057] The other end of the limiting plate 31 is fixedly provided with a driving motor 30, and the output end of the driving motor 30 penetrates through the limiting plate 31 and is fixedly connected with the gear 32.

[0058] The circular plate 18 is rotationally connected with the spinneret 5 through a rotating shaft 29, the end of the circular plate 18 is fixedly connected with a guide column 28, the end of the spinneret 5 is provided with a guide groove 33, and one end of the guide column 28 extends into the guide groove 33, so that the rotating range of the circular plate 18 can be limited through the guide groove 33 and the guide column 28.

[0059] The working principle of the device is as follows:

[0060] When the polymer melt is opened, the polymer melt in the screw extruder 1 enters into the tube 6, the heating wire 7 in the spinneret 5 heats the polymer melt in the tube 6 to prevent solidification caused by too low temperature, the polymer melt in the tube 6 enters into the nozzle 4, and then the polymer melt is sprayed to the throat 14 of the Laval nozzle 15 through the jet hole 13, the external cold gas source continuously sends cold gas into the cold gas pipe 8, the cold gas in the cold gas pipe 8 enters into the inside of the Laval nozzle 15 through the air pipe 16, the flow rate of the cold gas is greatly increased after passing through the throat 14 of the Laval nozzle 15, the high-speed cold gas stretches the polymer melt after passing through the throat 14 of the Laval nozzle 15, and then the superfine fiber with small average diameter is formed, meanwhile, the cold gas can cool the fiber, the gas in the conical cover 22 flows into the fixed box 26 through the through hole 23 under the negative pressure generated by the external negative pressure mechanism and the suction of the air pipe 24 and the four air suction pipes 25, and then the fiber is uniformly diffused to the surrounding, the opening rate of the polymer melt is improved, the air permeability and softness of the product are improved, and the fiber after opening can be uniformly sprayed to the receiving screen, so that the distribution of the fiber in the product is more uniform.

[0061] When the machine is stopped, the first telescopic cylinders 9 are extended, and the fixed plate 10, the sliding plate 11, the positioning plate 12 and the Laval nozzle 15 are moved horizontally until the nozzle 4 is moved to the outside of the Laval nozzle 15. The driving motor 30 drives the gear 32, the gear ring 27 and the circular plate 18 to rotate, and then drives the nozzle 4 and the sealing gasket 20 to rotate, and at the same time, the guide column 28 slides along the guide groove 33 until the guide column 28 is limited. At this time, the nozzle 4 is coaxial with the positioning tube 38, and the feeding end of the nozzle 4 is communicated with the material pipe 6. The second telescopic cylinder 40 is extended, and the cleaning column 21 is moved horizontally. When the cleaning column 21 slides into the nozzle 4, the residual polymer solution in the nozzle 4 is cleaned. The polymer solution enters the collecting box 36 through the spinneret hole 13 for collection. Until the tapered end of the cleaning column 21 abuts against the inner wall of the nozzle 4, the exhaust port of the exhaust passage 37 is communicated with the spinneret hole 13. The gas in the external gas source enters the exhaust passage 37 through the air inlet pipe 39, and then the polymer melt in the exhaust passage 37 and the spinneret hole 13 is cleaned. The cleaned polymer solution falls into the collecting box 36, realizing the function of quickly cleaning the residual polymer melt in the nozzle 4, and effectively preventing the nozzle 4 from being blocked.

[0062] When the machine is stopped, the first telescopic cylinders 9 are extended, and the fixed plate 10, the sliding plate 11, the positioning plate 12 and the Laval nozzle 15 are moved horizontally until the nozzle 4 is moved to the outside of the Laval nozzle 15. The driving motor 30 drives the gear 32, the gear ring 27 and the circular plate 18 to rotate, and then drives the nozzle 4 and the sealing gasket 20 to rotate, and at the same time, the guide column 28 slides along the guide groove 33 until the guide column 28 is limited. At this time, the nozzle 4 is coaxial with the positioning tube 38, and the feeding end of the nozzle 4 is communicated with the material pipe 6. The second telescopic cylinder 40 is extended, and the cleaning column 21 is moved horizontally. When the cleaning column 21 slides into the nozzle 4, the residual polymer solution in the nozzle 4 is cleaned. The polymer solution enters the collecting box 36 through the spinneret hole 13 for collection. Until the tapered end of the cleaning column 21 abuts against the inner wall of the nozzle 4, the exhaust port of the exhaust passage 37 is communicated with the spinneret hole 13. The gas in the external gas source enters the exhaust passage 37 through the air inlet pipe 39, and then the polymer melt in the exhaust passage 37 and the spinneret hole 13 is cleaned. The cleaned polymer solution falls into the collecting box 36, realizing the function of quickly cleaning the residual polymer melt in the nozzle 4, and effectively preventing the nozzle 4 from being blocked.

[0063] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the description of the present application.

Claims

1. A melt-blowing mechanism for melt-blowing ultrafine fibers, characterized by: The utility model provides an improved polypropylene fiber production device, which comprises a spinneret (5), a drawing assembly (3) and a screw extruder (1) arranged on the left and right sides of the spinneret (5) respectively, a cleaning assembly (2) arranged on the top of the spinneret (5), and a nozzle (4) arranged on the end of the spinneret (5) and capable of rotating along a horizontal line. When the nozzle (4) is rotated to the lower side, the two ports of the nozzle (4) are connected to the drawing assembly (3) and the material pipe (6) respectively. The drawing assembly (3) can improve the fiberizing rate of the polymer melt. When the nozzle (4) is rotated to the upper side, the cleaning assembly (2) can quickly clean the residual polymer melt in the nozzle (4). The drawing assembly (3) comprises a Laval nozzle (15) arranged in a horizontal sliding manner. A plurality of air injection pipes (16) are uniformly distributed on the outer wall of the air inlet end of the Laval nozzle (15) along the circumferential direction. One end of each air injection pipe (16) extends into the Laval nozzle (15). The air injection pipes (16) are connected to each other through a cold gas pipe (8). The air inlet of the cold gas pipe (8) is connected to an external cold gas source. A sealing ring (17) is sealingly connected to the inner wall of the air inlet end of the Laval nozzle (15). When the nozzle (4) is rotated to the lower side, the Laval nozzle (15) is coaxial with the nozzle (4). When the Laval nozzle (15) slides towards the nozzle (4), the discharge end of the nozzle (4) can pass through the sealing ring (17) and enter the inside of the Laval nozzle (15). The outer wall of the nozzle (4) abuts against the sealing ring (17). The gas injected into the air injection pipes (16) has a greatly increased flow rate after passing through the throat (14) of the Laval nozzle (15). The high polymer melt injected from the nozzle (4) is drawn by the high-speed airflow after passing through the throat (14) of the Laval nozzle (15). A fixing box (26) is arranged on the side of the Laval nozzle (15). A conical cover (22) is fixed horizontally in the fixing box (26). The opposite ends of the conical cover (22) extend to the outside through the fixing box (26). The small-diameter end of the conical cover (22) is coaxially fixed to the exhaust end of the Laval nozzle (15). A plurality of through holes (23) are uniformly distributed on the outer wall of the conical cover (22) in the fixing box (26) along the circumferential direction. The diameters of the through holes (23) gradually increase along the axial direction. The diameter of the through hole (23) closest to the Laval nozzle (15) is the smallest. The ends of the fixing box (26) are fixed at the four corners and provided with air suction pipes (25) connected to the inner cavities of the fixing box (26). The air suction pipes (25) are connected to each other through an air duct (24). One end of the air duct (24) is connected to an external negative pressure fan. The fibers drawn by the drawing assembly spread in all directions under the suction of the negative pressure gas when passing through the conical cover (22), so that the fibers are uniformly sprayed onto the receiving screen.

2. The meltblowing mechanism for meltblown ultrafine fibers according to claim 1, characterized by: The cleaning assembly (2) comprises a positioning tube (38) fixed horizontally on the top of the spinneret (5), the inner diameter of the positioning tube (38) is equal to the inner diameter of the feeding end of the nozzle (4), a cleaning column (21) is slidably arranged inside the positioning tube (38) and is in frictional abutment with the inner wall of the positioning tube (38), one end of the cleaning column (21) is in conical structure, an exhaust passage (37) is arranged through the cleaning column (21), the exhaust port of the exhaust passage (37) is coaxially arranged with the cleaning column (21), the air inlet of the exhaust passage (37) is fixedly connected with an air inlet pipe (39), and the air inlet pipe (39) is connected with an external gas source. When the nozzle (4) is rotated to the upper side, the nozzle (4) is coaxial with the positioning tube (38), the feeding end of the nozzle (4) is communicated with the positioning tube (38), when the cleaning column (21) slides to the direction close to the nozzle (4), the cleaning column (21) cleans the residual material in the nozzle (4), when the cleaning column (21) slides horizontally to the conical end and abuts against the nozzle (4), the exhaust port of the exhaust passage (37) is communicated with the spinneret hole (13) of the nozzle (4), and the gas in the exhaust passage (37) cleans the residual material in the spinneret hole (13).

3. The meltblowing mechanism for meltblown ultrafine fibers according to claim 2, characterized by: The end of the spinneret (5) is rotatably arranged with a circular plate (18) in frictional abutment with the end face of the spinneret (5), the nozzle (4) is arranged through the end of the circular plate (18), the feeding end of the nozzle (4) is in frictional abutment with the end face of the spinneret (5), the end of the circular plate (18) is provided with a circular groove (19), the circular groove (19) is fixedly provided with a sealing gasket (20), and when the nozzle (4) is rotated to be coaxial with the positioning tube (38), the sealing gasket (20) abuts against the port of the material pipe (6).

4. The melt-blowing mechanism for melt-blowing ultra-fine fibers according to claim 3, wherein: The top of the spinneret (5) is provided with two oppositely arranged arc-shaped plates (34) which are symmetrically arranged along the axial section of the positioning tube (38), both the arc-shaped plates (34) are fixedly connected with the positioning tube (38), and the nozzle (4) and the sealing gasket (20) can be in frictional abutment with the two arc-shaped plates (34) during the rotation of the circular plate (18).

5. The meltblowing mechanism for meltblown ultrafine fibers according to claim 1, characterized by: A plurality of electric heating wires (7) are fixedly arranged in the spinneret (5), the electric heating wires (7) are arranged on both sides of the material pipe (6), and the electric heating wires (7) can heat the high polymer melt in the material pipe (6) to prevent solidification.

6. The meltblowing mechanism for meltblown ultrafine fibers according to claim 2, characterized by: The spinneret (5) is detachably provided with a collecting box (36) which is provided with an opening at the top, when the nozzle (4) is rotated to the upper side, the spinneret hole (13) of the nozzle (4) is located above the collecting box (36).

7. The meltblowing mechanism for meltblown ultrafine fibers according to claim 1, characterized by: The bottom of the spinneret (5) is slidably provided with a sliding plate (11), one end of the sliding plate (11) extends to the outside of the spinneret (5) and is fixedly connected with a vertically arranged positioning plate (12), and the Laval nozzle (15) is fixedly inserted into the positioning plate (12).

8. The meltblowing mechanism for meltblown ultrafine fibers according to claim 3, characterized by: The outer wall of the circular plate (18) is fixedly sleeved with a gear ring (27), the end of the spinneret (5) is fixedly provided with a limiting plate (31), and the end of the limiting plate (31) is rotationally provided with a gear (32) engaged with the gear ring (27).

9. The meltblowing mechanism for meltblown ultrafine fibers according to claim 8, characterized by: The circular plate (18) is rotationally connected with the spinneret (5) through a rotating shaft (29), the end of the circular plate (18) is fixedly connected with a guide column (28), the end of the spinneret (5) is provided with a guide groove (33), one end of the guide column (28) extends into the guide groove (33), and the rotation range of the circular plate (18) can be limited through the guide groove (33) and the guide column (28).

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