Novel separated screw for single-screw extruder

Abstract

The utility model discloses a novel separated screw for a single screw extruder, which comprises a screw body, and main screw flights and auxiliary screw flights which are arranged on the screw body, the main screw flights and the auxiliary screw flights are arranged on the screw body in a staggered manner, a solid phase groove and a liquid phase groove are respectively arranged between the auxiliary screw flights and two adjacent main screw flights, and the solid phase groove and the liquid phase groove are communicated with each other. And the auxiliary screw flights are bent downwards towards the direction of the liquid phase groove to form an arc-shaped surface. The structure of the auxiliary screw flight is improved, the shape of the auxiliary screw flight is similar to a parabola, the shearing action borne by materials when the materials flow through the gap between the main screw flight and the auxiliary screw flight is greatly reduced, the temperature of the materials can be controlled, in addition, the materials can be stretched to flow, the materials can be mixed, and the extrusion effect of the materials is improved.

Description

Technical Field

[0001] The utility model relates to a single-screw extruder, and particularly to a novel separated screw for a single-screw extruder. Background Art

[0002] The single-screw extruder is the most widely used extruder in plastic extrusion molding. In order to improve the performance of the single-screw extruder, people have continuously improved the core component of the single-screw extruder - the screw for a long time, and various novel screws have emerged. Among many novel screws, the separated screw (also known as the barrier screw) has the greatest influence. Since this screw can separate the solid and liquid phases during plastic melting, it can improve the plasticizing efficiency and extrusion output. In addition, when the material passes over the barrier thread (also known as the secondary thread), it will experience a strong shearing effect, thereby improving the plasticizing quality. Due to these characteristics of the separated screw, this screw is still widely used so far.

[0003] As Figure 1 shown, the separation section structure of the screw body 1 of the existing separated screw is mainly composed of two threads with different lead sizes. The thread with a smaller lead is the main thread 3, and the thread with a larger lead is the secondary thread 4. The working principle of the separation section: when the screw rotates, the material is conveyed forward and gradually melted. The melted material will cross the secondary thread 4 slightly lower than the main thread 3 from the solid-phase groove 5 and enter the liquid-phase groove 6. As the material continues to melt, the solid-phase groove 5 becomes narrower and the liquid-phase groove 6 becomes wider until the material is completely plasticized.

[0004] Figure 2 It is a main and secondary thread diagram of a separated screw. The shape of its secondary thread is generally similar to that of the main thread, but only shorter than the main thread. When the material flows through the gap between the main and secondary threads, it will be subjected to a large shearing effect. In recent years, due to the increasing popularity of flame-retardant materials, the viscosity of flame-retardant materials is relatively large. When the material flows through the gap between the main and secondary threads, it will generate a large amount of shear heat, resulting in high material temperature and decomposition. Especially when the screw speed is relatively fast, the temperature is very difficult to control, resulting in the extrusion effect of the single-screw extruder not being guaranteed. Summary of the Invention

[0005] Object of the Invention: In order to overcome the deficiencies existing in the prior art, a novel separated screw for a single-screw extruder is provided. The structure of its secondary thread is improved, and the shape is similar to a parabola. The shearing effect suffered by the material when flowing through the gap between the main and secondary threads is greatly reduced, so that the material temperature can be controlled. In addition, the material can have a stretching flow, which is beneficial to mixing the material and improving the extrusion effect of the material.

[0006] Technical solution: To achieve the above object, the present utility model provides a novel separable screw for a single-screw extruder, which includes a screw body, a main thread and an auxiliary thread arranged on the screw body. The main thread and the auxiliary thread are arranged alternately on the screw body. A solid-phase groove and a liquid-phase groove are respectively arranged between the auxiliary thread and two adjacent main threads. The auxiliary thread bends downward towards the liquid-phase groove to form an arc surface.

[0007] Further, the top end of the arc surface is located at the top end of the auxiliary thread, and the bottom end is located at the bottom of the liquid-phase groove.

[0008] Further, the outer diameter of the main thread is larger than that of the auxiliary thread.

[0009] Further, the screw body is located inside the barrel. There is a gap between the main thread and the auxiliary thread and the barrel. The gap between the main thread and the barrel is smaller than the gap between the auxiliary thread and the barrel.

[0010] Further, the depth of the solid-phase groove is smaller than the depth of the liquid-phase groove.

[0011] Beneficial effects: Compared with the prior art, the present utility model improves the structure of the auxiliary thread. The shape of the improved auxiliary thread is similar to a parabola, which greatly reduces the shear force on the material when it flows through the gap between the main and auxiliary threads, avoids the increase in the material temperature caused by excessive shear heat, not only ensures the stable control of the material temperature, but also enables the material to have a stretching flow, which is beneficial to mixing the material and improves the material extrusion effect. Description of the drawings

[0012] Figure 1 It is a schematic structural diagram of a separable screw;

[0013] Figure 2 It is a schematic structural diagram of the main and auxiliary threads in the existing separable screw;

[0014] Figure 3 It is a schematic structural diagram of the main and auxiliary threads in the present utility model. Specific implementation manners

[0015] The following further clarifies the present utility model in conjunction with the drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present utility model and not to limit the scope of the present utility model. After reading the present utility model, various equivalent forms of modification by those skilled in the art fall within the scope defined by the appended claims of this application.

[0016] Such as Figure 1 And Figure 3As shown in the figure, the utility model provides a new type of separable screw for a single-screw extruder, which includes a screw body 1, a main thread 3 and an auxiliary thread 4 arranged on the screw body 1. The main thread 3 and the auxiliary thread 4 are arranged alternately on the screw body. A solid-phase groove 5 and a liquid-phase groove 6 are respectively arranged between the auxiliary thread 4 and two adjacent main threads 3. The auxiliary thread 4 bends downward towards the liquid-phase groove 6 to form an arc surface 7. The top end of the arc surface 7 is located at the top end of the auxiliary thread 4, and the bottom end is located at the bottom of the liquid-phase groove 6. The outer diameter of the main thread 3 is larger than that of the auxiliary thread 4. The screw body 1 is located in the barrel 2. There is a gap between the main thread 3 and the auxiliary thread 4 and the barrel 2. The gap between the main thread 3 and the barrel 2 is smaller than the gap between the auxiliary thread 4 and the barrel 2. That is to say, the main thread 3 is higher than the auxiliary thread 4. The depth of the solid-phase groove 5 is smaller than the depth of the liquid-phase groove 6.

[0017] In this embodiment, the above new type of separable screw is installed and applied in a single-screw extruder, and the material is extruded by the rotation of the screw body 1. During this process, the material is conveyed forward and gradually melted. The melted material enters the solid-phase groove 5 through the gap between the main thread 3 and the barrel 2, and then enters the liquid-phase groove 6 through the gap between the auxiliary thread 4 and the barrel 2 and through the arc surface 7 of the auxiliary thread 4, and so on until the material is completely plasticized and finally extruded.

[0018] During the above material extrusion process, due to the improved design structure of the arc surface 7, the shear force on the material flowing through the gap between the main and auxiliary threads is greatly reduced, especially when passing over the auxiliary thread 4. Therefore, the increase in the material temperature caused by excessive shear heat is avoided. It not only ensures the stable control of the material temperature during the entire extrusion process, but also enables the material to have tensile flow, which is beneficial to mixing the material and improves the material extrusion effect.

Claims

1. A novel separating screw for a single screw extruder, comprising a screw body and a main screw ridge and a secondary screw ridge arranged on the screw body, wherein the main screw ridge and the secondary screw ridge are arranged alternately on the screw body, and a solid phase groove and a liquid phase groove are respectively arranged between the secondary screw ridge and two adjacent main screw ridges, characterized in that: The auxiliary screw fins are bent downward toward the liquid phase tank to form an arc-shaped surface.

2. A novel separating screw for a single screw extruder according to claim 1, characterized in that: The top end of the arc-shaped surface is located at the top end of the auxiliary screw rib, and the bottom end is located at the bottom of the liquid phase tank.

3. A novel separating screw for a single screw extruder according to claim 1, characterized in that: The outer diameter of the main screw flight is greater than the outer diameter of the secondary screw flight.

4. A novel separating screw for a single screw extruder according to claim 1, characterized in that: The screw body is located in the barrel, and there is a gap between the main screw rib and the secondary screw rib and the barrel, and the gap between the main screw rib and the barrel is smaller than the gap between the secondary screw rib and the barrel.

5. A novel separating screw for a single screw extruder according to claim 1, characterized in that: The depth of the solid phase tank is smaller than the depth of the liquid phase tank.

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