A powder feeding system for a twin-screw extruder

Abstract

This utility model belongs to the field of mechanical processing, specifically relating to a powder feeding system for a twin-screw extruder. The system includes a main extruder and a feeding hopper. The feeding hopper is connected to the side of the main extruder, and its central axis is inclined at a 130°~140° angle to the vertical direction. It has a feed inlet at its top and a discharge outlet at its bottom. The diameter of the discharge outlet is smaller than that of the feed inlet and faces the mixing chamber inlet of the main extruder. Two parallel helical push screws are symmetrically arranged above the discharge outlet along the central axis of the feeding hopper. A fixing member is connected to the bottom of the helical push screws, and the fixing member is connected to the bottom of the feeding hopper. The extension direction of the helical push screws is the same as the axial direction of the feeding hopper. A connecting screw is connected to the discharge outlet, and the extension direction of the connecting screw is the same as that of the main extruder. Both ends of the connecting screw are rotatably connected to the inner wall of the discharge outlet via a rotating shaft. This utility model can effectively reduce material blockage at the feed inlet during powder processing.

Description

Technical Field

[0001] This utility model belongs to the field of mechanical processing, and specifically relates to a powder feeding system for a twin-screw extruder. Background Technology

[0002] As a core processing equipment in the plastics, chemical, and coating industries, the stability and efficiency of the feeding system of twin-screw extruders directly affect product quality and production efficiency. Titanium dioxide, as an inorganic chemical pigment, plays an important role in coloring, masking, and aging retardation in coatings, plastics, inks, and papermaking. Dispersibility is a key indicator determining whether titanium dioxide can exhibit optimal performance in various application areas. Twin-screw extruders are the most common mixing and dispersing equipment for titanium dioxide in the plastics field. Because titanium dioxide particles are small, with diameters mostly between 180nm and 260nm, and the PC resin powder and PVC resin powder used with it also have relatively small particles, their dry powder flowability is relatively poor, making feeding difficult and prone to accumulation and blockage at the twin-screw extruder feed inlet. In recent years, the industry has proposed various technical solutions to address problems such as feed blockage and poor powder flowability, but the problem of powder accumulation due to traditional gravity feeding methods still exists.

[0003] In existing technologies, twin-screw extruders mostly employ vertical gravity feeding (90° feed funnel). For example, patent CN222022160U achieves automated feeding by driving a rotating plate with an electric motor. While this improves operational efficiency, it does not solve the problem of feed inlet accumulation caused by poor flowability of small-particle-size powders (such as titanium dioxide, with a particle size of 180-260nm). Similarly, patent CN202323624193 sets up stirring blades and a screw in the feed hopper, which can alleviate clogging. However, the multi-stage stirring structure relying on a single drive shaft is complex, has high maintenance costs, and does not have an angle design optimized for powder flowability. Patent CN221985801U enhances material continuity by using the difference in inner diameter between the feed section and the compaction section, but it does not solve the problem of insufficient flowability of powders due to electrostatic adsorption or small particle size, and its applicability is particularly limited for high-value-added pigments such as titanium dioxide.

[0004] In summary, existing twin-screw extruder feeding systems rely on gravity or a single stirring structure, which cannot effectively improve the dry powder flowability of small-particle materials such as titanium dioxide. They suffer from insufficient powder flowability and are prone to causing material blockage at the feed inlet.

[0005] Therefore, there is an urgent need to propose a powder feeding system for twin-screw extruders to improve powder flowability and reduce the risk of material blockage. Utility Model Content

[0006] To address the aforementioned issues, this invention proposes a powder feeding system for a twin-screw extruder. Through optimized tilt angles (130°~140°) and a multi-stage spiral pushing structure (twin screws at the bottom + connecting screw at the end), it significantly improves powder flowability and reduces the risk of material blockage. Compared to existing technologies, this invention balances structural simplicity, industrial applicability, and dynamic adjustment capabilities, providing an innovative solution for the continuous and efficient processing of high-requirement powders such as titanium dioxide.

[0007] The technical solution of this utility model includes the following:

[0008] This utility model provides a powder feeding system for a twin-screw extruder, including: a main unit and a feeding hopper. The feeding hopper is connected to the side of the main unit. The central axis of the feeding hopper is inclined at an angle of 130° to 140° with the vertical direction. The top of the feeding hopper is provided with a feeding port and the bottom is provided with a discharging port. The main unit is provided with a mixing chamber. The diameter of the discharging port is smaller than that of the feeding port and faces the inlet of the mixing chamber of the main unit.

[0009] Two parallel spiral push screws are symmetrically arranged above the discharge port along the central axis of the feed funnel. The bottom of the spiral push screws is connected to a fixing member, which is connected to the bottom of the feed funnel. The extension direction of the spiral push screws is the same as the axial direction of the feed funnel.

[0010] A connecting screw is connected to the discharge port. The connecting screw extends in the same direction as the main unit. Both ends of the connecting screw are rotatably connected to the inner wall of the discharge port via a rotating shaft.

[0011] In some embodiments, the diameter of the feed inlet is φ250mm~φ350mm;

[0012] In some embodiments, the diameter of the discharge port is φ80mm~φ120mm.

[0013] In some embodiments, the length of the spiral pusher screw is 2 / 3 to 3 / 4 of the axial length of the feed funnel.

[0014] In some embodiments, the diameter of the helical push screw and the connecting screw is φ10mm~φ20mm.

[0015] In some embodiments, the pitch of the helical push screw and the connecting screw is 10mm to 30mm, and the helical direction is opposite to the rotation direction of the main screw.

[0016] In some embodiments, the helical push screw is connected to an independent servo motor, which is mounted on the host and is drivenly connected to the helical push screw.

[0017] In some embodiments, the surfaces of the helical push screw and the connecting screw are covered with a nano-ceramic wear-resistant layer, the thickness of which is 50μm~100μm and the surface roughness Ra≤0.2μm.

[0018] In some embodiments, 3 to 4 pressure sensors are evenly distributed circumferentially on the inner wall of the feed funnel at a height of 1 / 3 from the feed inlet. The independent servo motor is equipped with a control module, and the pressure sensors are connected to the control module.

[0019] In some embodiments, the inner wall of the feed funnel is further provided with a plurality of detachable guide plates. The guide plates extend downward from the edge of the feed inlet and are connected to the inner wall of the feed funnel by a snap-fit ​​structure or bolts. The inclination angle of the plate surface relative to the inner wall of the feed funnel is 20° to 35°.

[0020] The beneficial effects of this utility model are:

[0021] This utility model's twin-screw extruder powder feeding system improves the feeding performance of difficult-to-flow powders through a unique combination of an inclined funnel structure, a double-helix pusher screw, and a connecting screw. The combination of the inclined funnel, the double-helix pusher screw, and the connecting screw effectively solves the problems of bridging and adhesion of difficult-to-flow powders, ensuring smooth powder feeding and stable, uniform, and controllable feeding. This provides a guarantee for the stable and efficient operation of the twin-screw extruder, and is conducive to improving extrusion production efficiency and product quality.

[0022] This invention summarizes various aspects of the embodiments and should not be construed as limiting the claims. Other embodiments are conceivable based on the technology described herein, as will be apparent to those skilled in the art upon studying the following drawings and detailed description, and these embodiments are intended to be included within the scope of this invention.

[0023] Upon studying the following description, claims and drawings, those skilled in the art will understand and recognize these and other aspects, objects and features of this disclosure. Attached Figure Description

[0024] To gain a more complete understanding of the embodiments of this utility model, reference should be made to the embodiments described in more detail in the accompanying drawings and by way of example below, wherein:

[0025] Figure 1 The image shown is a front view of the powder feeding system of the twin-screw extruder of this utility model;

[0026] Figure 2 The figure shown is a side cross-sectional view of the powder feeding system of the twin-screw extruder of this utility model.

[0027] Explanation of reference numerals in the attached figures

[0028] 1. Main unit; 2. Feed hopper; 201. Feed inlet; 202. Discharge outlet; 203. Spiral pusher screw; 204. Connecting screw; 205. Gear. Detailed Implementation

[0029] The following describes embodiments of the present disclosure. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various alternative forms. The drawings are not necessarily drawn to scale; certain functions may be exaggerated or minimized to show details of specific components. Therefore, the specific structural and functional details disclosed in this utility model should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art to use the utility model in various ways. As those skilled in the art will understand, various features shown and described with reference to any of the drawings may be combined with features shown in one or more other drawings to produce embodiments not explicitly shown or described. The combinations of features shown provide representative embodiments for typical applications. However, various combinations and modifications of features consistent with the teachings of this disclosure may be desirable for certain particular applications or implementations.

[0030] Furthermore, in this invention, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements may include not only those elements but also elements not expressly listed or inherent to such processes, methods, articles, or apparatuses.

[0031] In this utility model, the "main machine" refers to the main machine of a "twin-screw extruder".

[0032] One or more embodiments of the present invention will now be described with reference to the accompanying drawings.

[0033] This utility model provides a powder feeding system for a twin-screw extruder, such as... Figure 1 and Figure 2 As shown, it includes:

[0034] The main unit 1 and the feeding hopper 2 are connected to the side of the main unit 1. The central axis of the feeding hopper 2 is inclined at an angle of 130° to 140° with the vertical direction. The top of the feeding hopper 2 is provided with a feeding port 201 and the bottom is provided with a discharging port 202. The main unit 1 is provided with a mixing chamber. The diameter of the discharging port 202 is smaller than that of the feeding port 201 and faces the entrance of the mixing chamber of the main unit 1.

[0035] Two parallel spiral push screws 203 are symmetrically arranged above the discharge port 202 along the central axis of the feed funnel 2. The bottom of the spiral push screw 203 is connected to a fixing member, which is connected to the bottom of the feed funnel 2. The extension direction of the spiral push screw 203 is the same as the axial direction of the feed funnel 2.

[0036] A connecting screw 204 is connected to the discharge port 202. The connecting screw 204 extends in the same direction as the main unit 1. Both ends of the connecting screw 204 are rotatably connected to the inner wall of the discharge port via a rotating shaft.

[0037] This invention defines the core structure of a powder feeding system for a twin-screw extruder. By combining an inclined funnel with a twin-helix pusher screw 203 and a connecting screw 204, the existing 90° gravity feeding method is replaced with a 130°~140° lateral screw-driven feeding method. This change in feeding method increases the feeding driving force, alters the dry powder flowability of titanium dioxide and other resin powders used in conjunction with it, and reduces or avoids material blockage at the feed inlet 201 during powder processing in the twin-screw extruder, achieving stable and controllable powder feeding. The inclined angle design facilitates the feeding of difficult-to-flow powders, the twin-helix pusher screw 203 ensures the metering and conveying of powder, and the connecting screw 204 achieves effective connection with the main screw 1. The connecting screw 204 is located at the discharge port 202 of the feed funnel 2, coaxial with the main screw and with threaded clearance engagement. Its core function is to achieve a seamless transition of material from the feeding system to the mixing chamber of the main screw 1. It guides the material pushed from the feed hopper 2 gradually into the threaded groove of the main screw through rotation, avoiding material accumulation or blockage at the junction and ensuring continuous and stable feeding. Furthermore, the thread of the connecting screw 204 engages with the surface of the main screw, and their coordinated rotation applies pre-compression force to the titanium dioxide, initially compacting the loose material. This provides a more uniform material flow for the subsequent melting and mixing stage of the main screw, reducing energy consumption in the feeding section. The clearance fit between the thread of the connecting screw 204 and the main screw also creates a mechanical seal, preventing molten material in the high-pressure mixing chamber from flowing back to the feeding section due to pressure difference, maintaining system pressure balance and process stability. Moreover, through the meshing motion of the connecting screw 204 and the main screw, the material undergoes moderate shearing and dispersion before entering the mixing chamber, promoting initial mixing while avoiding fluctuations caused by sudden changes in feed rate, thus improving the uniformity of the final product. Finally, the axial alignment design of the connecting screw 204 (coaxial with the main screw) reduces the complexity of the mechanical structure and shares the mechanical load of the main screw in the feeding section, allowing the main screw to focus more on the mixing and plasticizing tasks under high temperature and high pressure, thus extending the equipment life.

[0038] In some embodiments, the two spiral push screws 203 are connected to the feed funnel 2 via symmetrically arranged fixed seats 301, wherein the fixed seats 301 include:

[0039] Bearing mounting part: welded to the inner wall of the feed funnel 2 near the discharge port 202, and provided with bearing mounting holes that match the diameter of the spiral push screw 203;

[0040] Flange connection: Located on the outer side wall of the feed hopper 2, coaxial with the bearing mounting part, and fixed by bolts;

[0041] The bottom end of the spiral push screw 203 is embedded in the bearing mounting part through a rolling bearing, and the top end is rigidly connected to the output shaft of the drive device (such as an independent servo motor) through a flange, and the flange is fixed on the flange connection part.

[0042] In some embodiments, the diameter of the feed inlet 201 is φ250mm~φ350mm.

[0043] In some embodiments, the diameter of the discharge port 202 is φ80mm~φ120mm.

[0044] The specific diameters of the feed inlet 201 and the discharge outlet 202 are matched with the conical structure of the feed funnel 2, so that the feed inlet 201 has a sufficient receiving area and the size of the discharge outlet 202 is well matched with the subsequent pushing and connecting mechanism, which is conducive to the aggregation and smooth discharge of powder and can further improve the stability of feeding.

[0045] In some embodiments, the length of the spiral pusher screw 203 is 2 / 3 to 3 / 4 of the axial length of the feed hopper 2. A specific length of the spiral pusher screw 203 can better help the powder to be fed and avoid the powder from clogging. If it is too short, it will not play a stirring role, and if it is too long, it will cause trouble for the feeding process.

[0046] In some embodiments, the diameters of the spiral push screw 203 and the connecting screw 204 are φ10mm~φ20mm. The screw size is adapted to the size of the discharge port 202 of the feed funnel 2 and the inlet size of the mixing chamber of the main unit 1, ensuring that the screw has sufficient conveying capacity while avoiding excessively large mechanism size, thus realizing a compact powder feeding system.

[0047] In some embodiments, the pitch of the spiral pusher screw 203 and the connecting screw 204 is 10mm to 30mm, and the spiral direction is opposite to the rotation direction of the main screw. A suitable pitch ensures effective conveying and metering of the powder, while the opposite spiral direction helps prevent powder backflow and improves feeding efficiency and stability.

[0048] In some embodiments, the spiral push screw 203 is connected to an independent servo motor, which is mounted on the host machine 1 and driven by the spiral push screw 203. Independent drive can precisely control the rotational speed of each screw, while coordinated adjustment ensures the synchronization of the feeding system with the host machine 1. Feeding parameters can be optimized according to different material characteristics and process requirements to achieve more precise powder feeding control.

[0049] In some embodiments, the surfaces of the spiral pusher screw 203 and the connecting screw 204 are covered with a nano-ceramic wear-resistant layer, the thickness of which is 50μm~100μm and the surface roughness Ra≤0.2μm.

[0050] The wear-resistant layer can significantly improve the wear resistance of the screw and extend its service life, especially when processing highly abrasive powders, which reduces maintenance costs and ensures the long-term stable operation of the system.

[0051] In some embodiments, 3-4 pressure sensors are evenly distributed circumferentially on the inner wall of the feeding hopper 2 at a height of 1 / 3 from the feed inlet 201. The independent servo motor is equipped with a control module, and the pressure sensors are connected to the control module of the servo motor. Pressure sensors are installed on the inner wall of the feeding hopper 2 and electrically connected to the servo motor control module. The pressure sensors can monitor the pressure inside the hopper in real time, providing a basis for intelligent control of the feeding system. Through pressure feedback, the rotational speed of the screw conveyor 203 can be adjusted in a timely manner to prevent material blockage or empty material, achieving more reliable powder feeding control.

[0052] In some embodiments, the inner wall of the feed hopper 2 is further provided with several detachable guide plates. The guide plates extend downward from the edge of the feed inlet 201 and are connected to the inner wall of the feed hopper 2 by a snap-fit ​​structure or bolts. The inclined direction of the plate surface is consistent with the rotation direction of the spiral push screw 203, and the inclined angle is 20°~35°. The guide plates can guide the powder to enter the main unit 1 more smoothly, reduce material accumulation and dead corners, and further optimize the uniformity of feeding.

[0053] In some embodiments, the spiral pusher screw 203 is installed at the bottom of the feed hopper 2, above the discharge port 202. For example, a protruding connecting part can be provided at the bottom of the feed hopper, and the center of the bottom of the spiral pusher screw 203 is connected to the connecting part to achieve the following: Figure 2As shown in the diagram, the powder enters the feed hopper 2 and is pushed towards the main unit 1 by the spiral push screw 203. It then enters the main unit 1 through the bottom gap of the two spiral push screws 203, thus preventing the powder from accumulating in the feed hopper 2. Afterward, the powder passes through the connecting screw 204 and enters the main unit 1. The connecting screw 204 effectively connects with the main screw of the main unit 1, ensuring that the powder smoothly enters the mixing chamber and avoiding problems such as material blockage and uneven feeding.

[0054] This utility model document is intended to illustrate how to use the disclosed technology and various embodiments, and is not intended to limit its true scope and equivalent spirit. Furthermore, the foregoing description is not exhaustive of all possibilities or to limit the scope of protection to the precise forms disclosed. Changes and variations are possible in accordance with the foregoing teachings. The selected and illustrated embodiments provide the best illustration of the principles of the technology and its practical application, and enable those skilled in the art to use the disclosed technology for various conceivable specific applications with various modifications. Therefore, various changes and modifications made to the above embodiments without substantially departing from the spirit and principles of the technology described herein are intended to be included within the scope of this disclosure.

Claims

1. A twin screw extruder powder feeding system characterized by, Includes a main unit (1) and a feeding hopper (2). The feeding hopper (2) is connected to the side of the main unit (1). The central axis of the feeding hopper (2) is inclined at an angle of 130°~140° to the vertical direction. The top of the feeding hopper (2) is provided with a feeding port (201) and the bottom is provided with a discharging port (202). The main unit (1) is provided with a mixing chamber. The diameter of the discharging port (202) is smaller than that of the feeding port (201) and faces the entrance of the mixing chamber of the main unit (1). Two parallel spiral push screws (203) are symmetrically arranged above the discharge port (202) along the central axis of the feed funnel. The bottom of the spiral push screw (203) is connected to a fixing member, which is connected to the bottom of the feed funnel (2). The extension direction of the spiral push screw (203) is the same as the axial direction of the feed funnel (2). A connecting screw (204) is connected to the discharge port (202). The connecting screw (204) extends in the same direction as the main unit (1). The two ends of the connecting screw (204) are rotatably connected to the inner wall of the discharge port through a rotating shaft.

2. The twin-screw extruder powder feeding system according to claim 1, characterized in that, The diameter of the feed inlet (201) is φ250mm~φ350mm.

3. The twin-screw extruder powder feeding system according to claim 1, characterized in that, The diameter of the discharge port (202) is φ80mm~φ120mm.

4. The twin-screw extruder powder feeding system according to claim 1, characterized in that, The length of the spiral pusher screw (203) is 2 / 3 to 3 / 4 of the axial length of the feed funnel (2).

5. The twin-screw extruder powder feeding system according to claim 1 or 2, characterized in that, The diameters of the spiral pusher screw (203) and the connecting screw (204) are φ10mm~φ20mm.

6. The twin-screw extruder powder feeding system according to claim 1, characterized in that, The pitch of the spiral pusher screw (203) and the connecting screw (204) is 10mm~30mm, and the spiral direction is opposite to the rotation direction of the main screw.

7. The twin-screw extruder powder feeding system according to claim 1, characterized in that, The spiral push screw (203) is connected to an independent servo motor, which is mounted on the host (1) and is connected to the spiral push screw (203) for transmission.

8. The twin-screw extruder powder feeding system according to claim 1, characterized in that, The surfaces of the spiral pusher screw (203) and the connecting screw (204) are covered with a nano-ceramic wear-resistant layer, the thickness of which is 50μm~100μm and the surface roughness Ra≤0.2μm.

9. The twin-screw extruder powder feeding system according to claim 7, characterized in that, Three to four pressure sensors are evenly distributed around the inner wall of the feed funnel (2) at a height of 1 / 3 from the feed inlet (201). The independent servo motor is equipped with a control module, and the pressure sensors are connected to the control module.

10. The twin-screw extruder powder feeding system according to claim 1, characterized in that, The inner wall of the feed hopper (2) is also provided with several detachable guide plates. The guide plates extend downward from the edge of the feed inlet. The guide plates are connected to the inner wall of the feed hopper (2) by a snap-fit ​​structure or bolts. The angle of inclination of the plate surface relative to the inner wall of the feed hopper (2) is 20°~35°.

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