High-efficiency high-speed plasticizing screw

Abstract

The efficient high-speed plasticizing screw comprises a rod body, a main thread and an auxiliary thread, the main thread and the auxiliary thread extend in a spiral mode, the rod body sequentially comprises a connecting section, a discharging section, a separating section, a metering section, a barrier section and a mixing section from front to back, and the main thread is distributed on the discharging section, the separating section and the metering section in the mode that the outer diameter is equal and unchanged; the auxiliary thread and the main thread form a solid phase groove and a liquid phase groove which spirally extend from front to back on the separation section, the separation section is divided into three separation sections with the lengths gradually decreased from front to back, the volume of the liquid phase groove is gradually increased in each separation section from front to back, and the volume of the solid phase groove is gradually decreased in each separation section from front to back; a plurality of mixing baffles which are arranged at intervals from front to back are arranged on the mixing section, and a plurality of mixing through holes used for dispersing material flow are formed in each mixing baffle; the single screw has the comprehensive processing capacity close to that of double screws, and efficient conveying, full plasticizing, uniform mixing and stable extrusion of materials in the high-speed extrusion process of the screw are achieved.

Description

Technical Field

[0001] This application relates to the field of plastic extrusion equipment technology, and in particular to a high-efficiency, high-speed plasticizing screw. Background Technology

[0002] Currently, there are two main types of plastic extruders on the market: single-screw and twin-screw. Although the latter has a higher capacity and is developing rapidly, due to its higher cost, many industries, such as the plastic pipe manufacturing industry with large volume and strict cost requirements, still mostly choose single-screw extruders. Its structure is simple, its design is flexible, its cost is low, and its production efficiency is high. It is indispensable for the processing and forming of various pipes, sheets, plates, and profiles. As long as the output increases, it can completely replace twin-screw extruders.

[0003] However, the output and plasticizing quality of existing conventional single-screw extruders, especially when processing specialty or recycled materials, often fall short of the demands for high-speed, high-efficiency production. Simply increasing screw speed and motor power can easily lead to uneven material plasticization, increased wear, and the presence of bubbles or crystal points in the finished product. In existing technologies, to improve plasticizing capacity, structures such as separation sections, barrier sections, or mixing sections are incorporated into the screw. However, if these structures are not designed properly, they may cause new problems such as excessively high melt temperature, large pressure fluctuations, limited capacity increases, or increased energy consumption. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this application is to provide a high-efficiency, high-speed plasticizing screw with high output, high plasticizing efficiency, good plasticizing effect, and suitability for high-speed rotation.

[0005] To achieve the above objectives, this application adopts the following technical solution: a high-efficiency, high-speed plasticizing screw, comprising a rod extending from front to back and a main thread extending helically from front to back along the rod. The rod is divided into a connecting section, a feeding section, a separating section, a metering section, a barrier section, and a mixing section from front to back. The outer diameter of the main thread is uniformly and continuously distributed in the feeding section, the separating section, and the metering section. A secondary thread extending helically from front to back is also provided on the separating section. The main thread and the secondary thread form a solid phase groove and a liquid phase groove extending helically from front to back, respectively, on the separating section. The structure is divided into three separation sections from front to back, with the length of each section decreasing sequentially from front to back. The volume of the liquid phase tank gradually increases from front to back within each separation section, while the volume of the solid phase tank gradually decreases from front to back within each separation section. The barrier section has several feed troughs and several discharge troughs that are alternately distributed along the circumference of the rod. The mixing section has several mixing baffles arranged at intervals from front to back, and each mixing baffle has several mixing through holes for dispersing the material flow. These mixing through holes are arranged at intervals around the circumference of the rod.

[0006] In the above technical solution, it is further preferred that the plurality of mixing through holes include a plurality of first mixing through holes that are radially inward from front to back and a plurality of second mixing through holes that are radially outward from front to back, wherein the plurality of first mixing through holes and the plurality of second mixing through holes are alternately distributed along the circumference of the rod.

[0007] In the above technical solution, it is further preferred that the first mixing through hole and the second mixing through hole have opposite inclination directions, and the included angle between the two and the axis of the rod is the same, which is 20°-30°.

[0008] In the above technical solution, it is further preferred that the lead of the main thread of the feeding section is greater than the lead of the main thread of the metering section; and within each of the separation sections, the lead of the main thread is less than or equal to the lead of the auxiliary thread.

[0009] In the above technical solution, it is further preferred that the bottom diameter of the feeding section gradually increases and then gradually decreases from front to back.

[0010] In the above technical solution, it is further preferred that the length of the separation section is one-half of the total length of the rod.

[0011] In the above technical solution, it is further preferred that, within the separation section, the outer diameter of the main thread is larger than the outer diameter of the auxiliary thread, and there is a height difference of 0.8mm-1.0mm between the two.

[0012] In the above technical solution, it is further preferred that each of the plurality of feeding grooves has an angle of 20°-30° with the axis of the rod body, and the plurality of feeding grooves and the plurality of discharging grooves are parallel to each other; the depth of the feeding grooves gradually increases from front to back, and the depth of the discharging grooves gradually decreases from front to back.

[0013] In the above technical solution, it is further preferred that, in the rotation direction of the feed trough, a first barrier protruding radially outward is formed between the feed trough and the upstream discharge trough, and a second barrier protruding radially outward is formed between the feed trough and the downstream discharge trough. The outer diameter of the first barrier is smaller than the outer diameter of the second barrier, and there is a height difference of 0.5mm-0.8mm between the two.

[0014] In the above technical solution, it is further preferred that each of the first barriers and each of the second barriers is provided with a plurality of connecting holes, each of the connecting holes fluidly connecting adjacent feed troughs and discharge troughs, and the axis of the connecting hole is perpendicular to the axis of the feed trough.

[0015] Compared with the prior art, this application achieves the following beneficial effects:

[0016] This application optimizes and combines the functional sections of the screw, enabling a single screw to achieve comprehensive processing capabilities close to those of a twin-screw extruder. This allows the screw to efficiently transport, fully plasticize, uniformly mix, and stably extrude materials during high-speed extrusion, making it particularly suitable for products with high yield and high requirements for plasticization quality. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a high-efficiency, high-speed plasticizing screw provided in an embodiment of this application;

[0018] Figure 2 For along Figure 1 A sectional view cut along line AA in the diagram;

[0019] Figure 3 for Figure 1 A magnified view of a portion of point B in the middle;

[0020] Figure 4 for Figure 1 A three-dimensional structural diagram of one of the mixing baffles in the mixing section of the process;

[0021] Figure 5 for Figure 1 A schematic diagram of the material feeding section in the middle;

[0022] Figure 6 for Figure 1 A schematic diagram of the unfolded segment in the diagram;

[0023] Figure 7 For along Figure 6 A sectional view cut by the CC line;

[0024] Figure 8 for Figure 1 A schematic diagram of the unfolded barrier segment;

[0025] Figure 9 For along Figure 8 A sectional view cut by the DD line;

[0026] Figure 10 For along Figure 8 A sectional view cut by the EE line;

[0027] Figure 11 For along Figure 8 A sectional view cut by the FF line.

[0028] The components are as follows: 1. Rod body; 11. Connecting section; 12. Feeding section; 13. Separation section; 131. First separation section; 132. Second separation section; 133. Third separation section; 14. Metering section; 15. Barrier section; 16. Mixing section; 2. Main thread; 3. Secondary thread; 41. Solid phase tank; 42. Liquid phase tank; 51. Feed trough; 52. Discharge trough; 53. First barrier; 54. Second barrier; 55. Connecting hole; 61. Mixing baffle; 62. First mixing through hole; 63. Second mixing through hole; 7. Connecting thread. Detailed Implementation

[0029] To illustrate the technical content, structural features, achieved objectives, and effects of the application in detail, the technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. In the following description, for illustrative purposes, numerous specific details are set forth to provide a detailed description of various exemplary embodiments or implementations of the invention. However, various exemplary embodiments may also be implemented without these specific details or in one or more equivalent arrangements. Furthermore, the various exemplary embodiments may differ, but are not necessarily exclusive. For example, the specific shape, structure, and characteristics of the exemplary embodiments may be used or implemented in another exemplary embodiment without departing from the inventive concept.

[0030] In the following description, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0031] This application provides a high-efficiency, high-speed plasticizing screw, such as Figure 1 As shown, the screw includes a rod body 1 extending from front to back and a main thread 2 extending spirally from front to back. When the screw rotates, the main thread 2 cooperates with the rod body 1 to convey material from front to back and shear and stir the material, so that the material is plasticized and melted into a melt for extrusion.

[0032] The rod body 1 consists of a connecting section 11, a feeding section 12, a separating section 13, a metering section 14, a barrier section 15, and a mixing section 16 from front to back. A main thread 2 starts from the feeding section 12, extends spirally through the separating section 13 to the metering section 14, and its outer diameter remains constant.

[0033] The connecting section 11 is used to connect to the extruder drive unit so that the entire screw can rotate about its own axis X1 under the drive of the drive unit. The rear end of the connecting section 11 is provided with a connecting thread 7 for assembly with the barrel.

[0034] like Figure 1 , 5 As shown, the main thread 2 of the feeding section 12 has a large lead, and its root diameter D1 is designed to gradually increase and then gradually decrease from front to back, forming a "drum-shaped" structure. This design facilitates smooth material feeding, initial compaction, and stable conveying, enabling the screw to achieve the feeding capacity of a twin-screw extruder, providing a stable and sufficient material flow for subsequent sections and improving the extruder's capacity. To improve the screw's wear resistance, the surface of the feeding section 12 can be treated with nitriding, hard alloy spraying, etc.

[0035] like Figure 1 , 6 As shown in Figure 7, the separation section 13 is one of the core plasticizing areas of the entire screw. The length of the separation section 13 accounts for half the length of the entire screw body 1, ensuring sufficient length for the material to undergo thorough solid-liquid phase separation. The separation section 13 is further subdivided into three sub-segments: the first separation segment 131, the second separation segment 132, and the third separation segment 133, whose lengths decrease sequentially.

[0036] In this section, a secondary thread 3 with the same direction of rotation as the main thread 2 but a different lead is added. The rear end face of the main thread 2 and the front end of the secondary thread 3 form a solid phase groove 41 with the surface of the rod body 1, while the rear end face of the secondary thread 3 and the front end of the main thread 2 form a liquid phase groove 42 with the surface of the rod body 1. Within each separation segment, the lead of the secondary thread 3 is greater than or equal to the lead of the main thread 2. By changing the lead of the secondary thread 3 and / or the bottom diameter of the rod body 1, the volume of the liquid phase groove 42 gradually increases from front to back, while the volume of the solid phase groove 41 gradually decreases from front to back, thereby achieving progressive compression, melting, and separation of the material. The solid phase is confined in the gradually decreasing solid phase groove 41 and continues to be heated, sheared, and melted, while the melt enters the gradually expanding liquid phase groove 42, and the gas is forced back and discharged from the feed port.

[0037] In this embodiment, the outer diameter of the auxiliary thread 3 is smaller than that of the main thread 2, and there is a height difference δ1 between them. In this embodiment, the height difference δ1 is 0.8mm-1.0mm, and the height difference δ1 of the first separation segment 131 is greater than the height difference δ1 of the second separation segment 132, which is greater than the height difference δ1 of the third separation segment 133. The most abundant solid phase in the first separation segment 131 melts and plasticizes into a liquid phase. As the material is conveyed backward, the amount of solid phase that needs to be melted gradually decreases. The third separation segment 133 has the least amount of solid phase. The trend of the height difference δ1 in the separation segment 13 conforms to the solid-liquid conversion trend of the material in the separation segment 13.

[0038] The separation section 13 uses a long-distance and multi-segment solid-liquid separation structure to perform progressive, controllable and efficient compression, melting and separation of materials, thereby achieving the efficient plasticization and high-quality plasticization effect of a twin-screw extrusion on a single screw.

[0039] The main thread 2 of metering section 14 has a small lead, and its main function is to meter and stably transport the basically plasticized melt, and establish a stable extrusion pressure for the melt.

[0040] like Figure 1 , 8 As shown in Figures 9, 10, and 11, a plurality of feed grooves 51 and a plurality of discharge grooves 52 are provided on the outer surface of the barrier section 15. The plurality of feed grooves 51 and the plurality of discharge grooves 52 are alternately distributed along the circumference of the rod body 1, and the plurality of feed grooves 51 and the plurality of discharge grooves 52 are parallel to each other and are all inclined to the axis X1 of the rod body 1. The feed groove 51 has an included angle α with the axis X1. In the embodiment of this application, the included angle α is 20°-30°.

[0041] In the spiral direction of the feed chute 51, a first barrier 53 protruding radially outward is formed between the feed chute 51 and the upstream discharge chute 52, and a second barrier 54 protruding radially outward is formed between the feed chute 51 and the downstream discharge chute 52. The inlet of the feed chute 51 is open, and its outlet is closed by the second barrier 54, with its depth gradually increasing from front to back. The inlet of the discharge chute 52 is closed by the first barrier 53, and its outlet is open, with its depth gradually decreasing from front to back. The outer diameter of the first barrier 53 is smaller than the outer diameter of the second barrier 54, and there is a height difference δ2 between them. In this embodiment, the height difference δ2 is 0.5mm-0.8mm. The height difference δ2 intensifies the shear force on the material when it crosses the first barrier 53 and the second barrier 54, thereby achieving secondary plasticization of the material.

[0042] In this embodiment, each first barrier 53 and each second barrier 54 has multiple connecting holes 55 that connect adjacent feed channels 51 and discharge channels 52. The axis of each connecting hole 55 is perpendicular to the axis of the feed channel 51. This structure forces the melt to pass through the connecting holes 55 when crossing the first barrier 53 or the second barrier 54. Together with the feed channels and discharge channels with gradually changing depths, the melt generates strong shearing, diversion, and mixing effects. In particular, the flow generated when passing through the connecting holes 55 is in an approximately shearing direction, which can effectively break up unmelted crystal points and achieve fine homogenization and secondary plasticization of the melt. The intense shearing generated by the barrier section 15 can reach the shearing force generated by the meshing of twin screws, effectively improving plasticizing efficiency, plasticizing effect, and production capacity.

[0043] like Figure 1-4 As shown, multiple mixing baffles 61 are fixed on the mixing section 16 at intervals from front to back. Each mixing baffle 61 protrudes radially outward from the outer surface of the rod body 1, forming a ring shape. Multiple first mixing through holes 62 and multiple second mixing through holes 63 are alternately formed along the circumference of the rod body 1 on each mixing baffle 61. The axis of the first mixing through hole 62 is inclined from front to back towards the center of the screw, forming an angle β1 with the axis X1; the axis of the second mixing through hole 63 is inclined from front to back towards the outer periphery of the screw, forming an angle β2 with the axis X1. The inclination directions of the first mixing through hole 62 and the second mixing through hole 63 are opposite, but their inclination angles are the same, with both angles β1 and β2 being 20°-30°.

[0044] The structural design of the mixing baffle 61 replaces the complex mixing channels formed by the intermeshing mixing protrusions in a twin-screw extruder. When the melt flows through the mixing section 16, it is alternately guided to the center and periphery by multiple first mixing through holes 62 and multiple second mixing through holes 63 on the mixing baffle 61, achieving dispersion. The melt then converges between adjacent mixing baffles 61, undergoing multiple changes in flow rate, flow direction, and convergence. This results in efficient distributed mixing under low shear, further homogenizing the melt temperature, eliminating flow marks, and improving the appearance and internal quality of the product.

[0045] In this application, during screw operation, material is efficiently conveyed from the feeding section 12 into the separation section 13, where solid-liquid phase separation, gas discharge, and bulk plasticization are completed. After stabilization in the metering section 14, it enters the barrier section 15 for high shear and mixing to ensure complete melting. Finally, it achieves thorough homogenization in the mixing section 16, ultimately being extruded into a high-quality, homogeneous melt. The synergistic effect of each functional section enables the single screw to possess comprehensive processing capabilities approaching those of a twin-screw extruder. This screw can operate at higher speeds, significantly increasing extrusion output while ensuring good plasticization quality and temperature uniformity of the melt, thereby improving the overall performance of the final product.

[0046] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made without departing from the spirit and scope of this application. The scope of protection claimed by this application is defined by the appended claims, specification, and their equivalents.

Claims

1. A high-efficiency, high-speed plasticizing screw, comprising a rod extending from front to rear and a main thread extending helically from front to rear along the rod, characterized in that, The rod body is divided into a connecting section, a feeding section, a separating section, a metering section, a barrier section, and a mixing section from front to back. The outer diameter of the main thread is evenly distributed in the feeding section, the separating section, and the metering section. The separating section is also provided with a secondary thread extending spirally from front to back. The main thread and the secondary thread form a solid phase tank and a liquid phase tank respectively extending spirally from front to back on the separating section. The separating section is divided into three separating segments from front to back, and the lengths of the three separating segments decrease sequentially from front to back. The volume of the liquid phase tank gradually increases from front to back in each separation section, and the volume of the solid phase tank gradually decreases from front to back in each separation section; the barrier section is provided with several feed troughs and several discharge troughs that are alternately distributed along the circumference of the rod; the mixing section is provided with several mixing baffles arranged at intervals from front to back, and each mixing baffle is provided with several mixing through holes for dispersing the material flow, and the several mixing through holes are arranged at intervals around the circumference of the rod.

2. The high-efficiency, high-speed plasticizing screw according to claim 1, characterized in that, The plurality of mixing through holes includes a plurality of first mixing through holes that are radially inward from front to back and a plurality of second mixing through holes that are radially outward from front to back. The plurality of first mixing through holes and the plurality of second mixing through holes are alternately distributed along the circumference of the rod.

3. The high-efficiency, high-speed plasticizing screw according to claim 2, characterized in that, The first mixing through hole and the second mixing through hole are inclined in opposite directions, and the angle between the two and the axis of the rod is the same, both being 20°-30°.

4. The high-efficiency, high-speed plasticizing screw according to claim 1, characterized in that, The lead of the main thread in the feeding section is greater than the lead of the main thread in the metering section; within each separation section, the lead of the main thread is less than or equal to the lead of the auxiliary thread.

5. The high-efficiency, high-speed plasticizing screw according to claim 1, characterized in that, The bottom diameter of the feeding section gradually increases and then gradually decreases from front to back.

6. The high-efficiency, high-speed plasticizing screw according to claim 1, characterized in that, The length of the separation section is one-half of the total length of the rod.

7. The high-efficiency, high-speed plasticizing screw according to claim 1, characterized in that, Within the separation section, the outer diameter of the main thread is larger than the outer diameter of the auxiliary thread, and there is a height difference of 0.8mm to 1.0mm between them.

8. The high-efficiency, high-speed plasticizing screw according to claim 1, characterized in that, Each of the aforementioned feed troughs has an angle of 20°-30° with the axis of the rod body, and the aforementioned feed troughs and the aforementioned discharge troughs are parallel to each other; the depth of the feed troughs gradually increases from front to back, and the depth of the discharge troughs gradually decreases from front to back.

9. The high-efficiency, high-speed plasticizing screw according to claim 8, characterized in that, In the spiral direction of the feed chute, a first barrier protruding radially outward is formed between the feed chute and the upstream discharge chute, and a second barrier protruding radially outward is formed between the feed chute and the downstream discharge chute. The outer diameter of the first barrier is smaller than the outer diameter of the second barrier, and there is a height difference of 0.5mm to 0.8mm between the two.

10. The high-efficiency, high-speed plasticizing screw according to claim 9, characterized in that, Each of the first barriers and each of the second barriers is provided with a plurality of connecting holes, each of the connecting holes being fluidly connected to the adjacent feed trough and the discharge trough, and the axis of the connecting hole is perpendicular to the axis of the feed trough.

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