WO2024087253A1

WO2024087253A1 - Extruder and extrusion processing method

Info

Publication number: WO2024087253A1
Application number: PCT/CN2022/130629
Authority: WO
Inventors: 徐百平; 梁瑞凤; 喻慧文; 肖书平; 谈灵操; 张春华; 黄卫杨
Original assignee: 五邑大学; 广东仕诚塑料机械有限公司
Priority date: 2022-10-24
Filing date: 2022-11-08
Publication date: 2024-05-02
Also published as: CN115923086A

Abstract

An extruder and an extrusion processing method, relating to the technical field of extruder devices. The extruder comprises a barrel (100) and a screw assembly; the screw assembly comprises a first screw (210) and a plurality of second screws (220), and the first screw (210) and the plurality of second screws (220) rotate in a same direction and are arranged in the barrel (100); the first screw (210) is meshed with the second screws (220), and meshing points are located on a plane formed by the rotation axes (230) of the first screw (210) and the second screws (220); the crest diameter of the first screw (210) is matched with the root diameters of the second screws (220) at the plane; the root diameter of the first screw (210) is matched with the crest diameters of the second screws (220) at the plane; the meshing points of the first screw (210) and the second screws (220) are always located in a plane formed by the two rotation axes, so that the maximum speed difference can be generated at the meshing points, thereby improving the meshing performance.

Description

Extruder and extrusion processing method

Technical Field

The present application relates to the technical field of extruder equipment, and in particular to an extruder and an extrusion processing method.

Background technique

Extruders are widely used in the fields of polymer materials, food, medicine, chemicals, etc., and are responsible for the melting, mixing and extrusion of materials. In order to ensure that the materials undergo similar processing history, control the residence time distribution, and prevent the materials from overheating and degradation, it is necessary to realize the self-cleaning function between the two screws. Therefore, the shape of the two screws must meet the requirements of geometric conjugation. However, the traditional twin-screw geometric modeling is based on the principle of relative motion. Although it can achieve mutual meshing between the twin screws and trigger the screw to self-clean through the meshing point, the speed difference between the two of the traditional twin screws does not reach the maximum when meshing, that is, the meshing performance does not reach the ideal state, and the meshing performance will affect the self-cleaning effect of the screw as well as the melting efficiency and dispersion and mixing effect. Therefore, the self-cleaning effect, melting efficiency and dispersion and mixing effect of the traditional extruder still need to be improved.

Summary of the invention

The main purpose of the embodiments of the present application is to provide an extruder and an extrusion processing method, aiming to improve the self-cleaning effect, melting efficiency and dispersion mixing effect of the extruder.

The extruder according to the first embodiment of the present application includes:

Barrel;

A screw assembly, the screw assembly comprising a first screw and a plurality of second screws, the first screw and the plurality of second screws all rotate in the same direction and are arranged in the barrel, the first screw and the second screw are meshed and the meshing point is located in the plane formed by the rotation axes of the first screw and the second screw; the top diameter of the first screw meshes with the root diameter of the second screw at the plane; the root diameter of the first screw meshes with the top diameter of the second screw at the plane.

According to the extrusion processing method of the second aspect of the present application, applied to any extruder described in the first aspect, the method includes:

Obtaining a speed ratio between the first screw and the second screw;

Controlling the first screw and the second screw to rotate in the same direction at the speed ratio so that the material entering from the barrel inlet is transferred to the barrel outlet and processed during the transfer process;

During the transmission process, the melting section of the barrel is monitored in real time for temperature;

Whether to adjust the heating power of the heating device disposed in the melting section is determined according to the result of temperature monitoring.

The extruder and extrusion processing method proposed in the present application control the first screw and the second screw to rotate in the same direction. When the first screw and the second screw are meshed, the two screws wipe each other, thereby realizing a self-cleaning function. Since the meshing point of the first screw and the second screw is always located in the plane formed by the two rotation axes, the first screw and the second screw rotate in opposite directions relative to each other at the meshing point, and when the root diameter of the first screw is meshed with the top diameter of the second screw or the top diameter of the first screw is meshed with the root diameter of the second screw, a maximum speed difference can be generated to improve the meshing performance. At this time, for the extruder barrel, the shearing effect caused by the speed difference can be fully utilized to provide more homoclinic orbits to trigger the chaotic mixing enhancement effect. Therefore, the embodiment of the present application can improve the self-cleaning effect of the extruder, the melting efficiency and the dispersion mixing effect of the multiphase system by improving the meshing performance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a combined structure of a first screw and a second screw with a rotation speed ratio of 2:1 provided in an embodiment of the present application (excluding a barrel);

FIG2 is a schematic diagram of the structure of a three-screw mechanism with a rotation speed ratio of 2:1 provided in an embodiment of the present application (excluding the barrel);

FIG3 is a schematic top view of the meshing point of the extruder shown in FIG1 in an embodiment of the present application;

FIG4 is a schematic diagram of the cross-sectional composition of the first screw of the extruder shown in FIG1 when meshing in an embodiment of the present application;

FIG5 is a schematic diagram of the cross-sectional composition of the second screw of the extruder shown in FIG1 when meshing in an embodiment of the present application;

FIG6 is a schematic top view of the extruder shown in FIG1 in an embodiment of the present application;

FIG7 is a schematic structural diagram of the screw shown in FIG1 in an embodiment of the present application when a kneading structure is provided;

8 is a schematic diagram of the cross-sectional composition of the first screw and the second screw when meshing in an extruder with a rotation speed ratio of 1:1 provided in an embodiment of the present application;

9 is a schematic diagram of the combined structure of the first screw and the second screw of the extruder with a rotation speed ratio of 1:1 provided in an embodiment of the present application (the screw includes a kneading structure);

FIG. 10 is a schematic flow chart of the extrusion processing method provided in an embodiment of the present application.

Reference numerals:

The barrel 100, the conveying section 110, the feed port 111, the melting section 120, the exhaust section 130, the exhaust port 131, the mixing and extruding section 140, the discharge port 141,

The first screw 210, the second screw 220, the rotation axis 230, the fold line 240, the kneading structure 250,

Runner 300.

Detailed ways

In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the technical field of the application. The terms used herein are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application. The terms "first", "second", "third", "fourth", etc. (if present) in the specification of the application and the above-mentioned drawings are used to distinguish similar objects, and need not be used to describe a specific order or sequential order.

In addition, the described features, structures or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, known methods, devices, implementations or operations are not shown or described in detail to avoid blurring the various aspects of the present disclosure.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

Extruders are widely used in polymer materials, food, medicine, chemicals and other fields, and are responsible for the melting, mixing and extrusion of materials. In order to ensure that the materials undergo similar processing history, control the residence time distribution, and prevent the materials from overheating and degradation, it is necessary to realize the self-cleaning function between the two screws. Therefore, the shape of the two screws must meet the requirements of geometric conjugation. However, the traditional twin-screw geometric modeling based on the principle of relative motion can achieve mutual meshing between the twin screws and trigger the screw to achieve self-cleaning through the meshing point. However, it has been found that from the perspective of the cross-section of the screw, it only ensures that the two screws are in contact at all times, and the meshing point cannot always be kept on the line connecting the rotation centers of the two screws. The speed difference between the traditional twin screws does not reach the maximum when meshing, and it is impossible to provide homoclinic orbital disturbance, which leads to the meshing performance not reaching the ideal state. The meshing performance will affect the self-cleaning effect of the screw, the melting efficiency and the dispersion and mixing effect. Therefore, the self-cleaning effect, melting efficiency and dispersion and mixing effect of the traditional extruder still need to be improved. Based on this, the present application proposes an extruder and an extrusion processing method, which can improve the self-cleaning effect of the extruder as well as the melting efficiency and the dispersion and mixing effect.

It should be noted that in Figures 1 to 9, O represents the rotation center of the first screw 210, and _O1 represents the rotation center of the second screw 220. Point Q is the meshing point of one of the cross sections when the first screw 210 and the second screw 220 are meshed, and is on the line connecting _O1O . The following cross sections all refer to the cross sections of the meshing area.

1 to 9 , the extruder proposed in the present application includes:

Barrel 100;

The screw assembly includes a first screw 210 and a plurality of second screws 220. The first screw 210 and the plurality of second screws 220 rotate in the same direction and are arranged in the barrel 100. The first screw 210 and the second screw 220 are meshed and the meshing point is located in the plane formed by the rotation axis 230 of the first screw 210 and the second screw 220; the top diameter of the first screw 210 is meshed with the root diameter of the second screw 220 at the plane; the root diameter of the first screw 210 is meshed with the top diameter of the second screw 220 at the plane.

Therefore, by controlling the first screw 210 and the second screw 220 to rotate in the same direction, when the first screw 210 and the second screw 220 are meshed, the two screws wipe each other, thereby realizing the self-cleaning function; since the meshing point of the first screw 210 and the second screw 220 is always located in the plane formed by the two rotation axes 230, the first screw 210 and the second screw 220 rotate in opposite directions relative to each other at the meshing point, and when the root diameter of the first screw 210 is meshed with the top diameter of the second screw 220 or the top diameter of the first screw 210 is meshed with the root diameter of the second screw 220, a maximum speed difference can be generated to improve the meshing performance. At this time, for the extruder, the shearing effect caused by the speed difference can be fully utilized to provide more homoclinic orbits to trigger the chaotic mixing enhancement effect; therefore, the embodiment of the present application can improve the self-cleaning effect of the extruder, the melting efficiency and the dispersion mixing effect of the multiphase system by improving the meshing performance.

It should be noted that "several" means at least one, and the second screw 220 can be one or more, and the embodiment of the present application does not limit this. In some embodiments, as shown in FIG. 2 , two second screws 220 are provided, and the two second screws 220 are respectively located on both sides of the first screw 210 and arranged in rows. In other embodiments, as shown in FIG. 1 , one second screw 220 is provided.

It should be noted that the top diameter represents the longest distance from the rotation center of the cross section passing through the rotation axis 230 to the corresponding edge profile, and the root diameter represents the corresponding shortest distance.

It should be noted that two straight lines can determine a unique plane, so the rotation axis 230 of the first screw 210 and the second screw 220 can uniquely determine a plane.

It should be noted that, in some embodiments, only the top diameter of the first screw 210 is meshed with the root diameter of the second screw 220, and the root diameter of the first screw 210 is meshed with the top diameter of the second screw 220. In other embodiments, when the curved segment between the top diameter and the root diameter on the first screw 210 and the second screw 220 passes through the plane formed by the rotation axis 230, there are multiple meshing points that mesh with each other. At this time, a meshing curve will be formed on the plane. For example, when the first screw 210 and the second screw 220 always remain meshed at the plane, at this time, a broken line 240 formed by continuous Z-shaped line segments as shown in Figure 3 will be formed on the plane.

It should be noted that, when rotating in the same direction, the polar diameter changes of the arc segments of the first screw 210 and the second screw 220 that are meshed with each other along the rotation direction are opposite, so that conjugation can be achieved. For example, for the first screw 210, when rotating toward the plane at time t, the polar diameter corresponding to its arc segment increases, and for the second screw 220, when rotating toward the plane at the same time t, the polar diameter corresponding to its arc segment decreases.

It should be noted that the meshing point is the point where the plane formed by the rotation axis 230 intersects when the first screw 210 and the second screw 220 are meshed. At this time, the value range of the distance between the meshing point located in the same cross section and the rotation center of the first screw 210 is the root diameter of the first screw 210 and the top diameter of the first screw 210. For example, assuming that the root diameter is r and the top diameter is R, the value range of the distance between the meshing point and the rotation center of the first screw 210 is [r, R]; when the first screw 210 and the second screw 220 are always meshed in this plane, the distance between the meshing point and the rotation center of the first screw 210 will gradually increase from r to R, and gradually decrease from R to r; and repeat this cycle.

It should be noted that, in some embodiments, the barrel 100 is an "8"-shaped structure formed by interpenetrating cylindrical holes with axes parallel to each other. The flow domain formed by the screw assembly and the inner wall of the barrel 100 will produce a periodic wedge-shaped extrusion effect on the wall surface near the upper and lower corners of the meshing point as the first screw 210 and the second screw 220 rotate periodically, thereby generating a tensile force field action mechanism, which can further effectively improve the dispersion and mixing effect and melting efficiency of the multiphase material system.

It should be noted that the first screw 210 , the second screw 220 and the barrel 100 form a flow channel 300 , and the flow channel 300 is used for the passage of materials.

It is understandable that the number of screws of the second screw 220 to the first screw 210 is inversely proportional to the rotational speed ratio of the first screw 210 to the second screw 220 .

It should be noted that the more heads the screw has, the more stable it is when rotating. Therefore, setting the head ratio and the speed ratio in inverse proportion can improve the meshing performance. For example, assuming that the speed ratio of the first screw 210 to the second screw 220 is 2, the number of heads of the second screw 220 is 2, and the number of heads of the first screw 210 is 1.

It is understandable that the top diameter of the first screw 210 is the same as the top diameter of the second screw 220 , and the root diameter of the first screw 210 is the same as the root diameter of the second screw 220 .

It can be understood that the cross-section of each meshing point of the first screw 210 and the second screw 220 is composed of an even number of circular arc segments and an even number of curved arc segments staggered together, and the radii of the circles corresponding to two adjacent circular arc segments are the root diameter and the top diameter, respectively; each curved arc segment on the same screw cross-section is a curved arc whose central angle changes linearly and at the same rate of change, and the two cross-sections that mesh with each other are symmetrically arranged along the line connecting the corresponding two rotation centers.

It should be noted that, for the central angles corresponding to multiple arc segments on the same screw cross section, all are the same, and “the central angle changes linearly and at the same rate of change” means that the rate of change of the central angle of the curved arc segment linearly changing from the top diameter to the root diameter is the same; exemplarily, for the second screw 220, the central angles corresponding to multiple arc segments on the second screw 220 are all the same, and the curved arc segments are all curved arcs whose central angles change linearly and at the same rate of change.

It should be noted that there is no restriction on the number of arc segments and curve segments of the first screw 210 and the second screw 220. In some embodiments, the first screw 210 and the second screw 220 have the same number of arc segments and the same number of curve segments, and the number of arc segments and the number of curve segments are irrelevant to the speed ratio. In other embodiments, the number of arc segments of the second screw 220 is k times the number of arc segments of the first screw 210, and the number of curve segments of the second screw 220 is k times the number of curve segments of the first screw 210, where k represents the speed ratio of the first screw 210 to the second screw 220. In this case, the number of arc segments and the number of curve segments are both related to the speed ratio.

It is understandable that the arc segment of the first screw 210 corresponds to the polar diameter

Wherein θ is the central angle corresponding to the curved arc segment of the first screw 210, R is the top diameter, and r is the root diameter; k is the speed ratio of the first screw 210 to the second screw 220; β is the maximum value of θ and the sum of β and the central angle corresponding to the adjacent arc segment is π.

For example, as shown in Figure 3, the polar diameter represents the distance from the rotation center on the cross section to the corresponding curved arc segment. When θ is 0, the polar diameter corresponds to the top diameter, and when θ is β, the polar diameter corresponds to the root diameter.

It should be noted that when the sum of β and the central angle corresponding to any arc segment is π, then for the first screw 210, the number of its arc segments is set to 1, and the number of curved arc segments is also set to 1. There is no restriction on the number of curved arc segments and the number of arc segments of the second screw 220. Referring to FIG4 , when the top diameter OB is located at the meshing point, when the first screw 210 rotates clockwise, the center angle θ decreases linearly in the counterclockwise direction. It should be noted that for the second screw 220, in order to keep the plane formed by the rotation axis 230 always meshing with the first screw 210, the polar diameter change of the curved arc segment of the first screw 210 is opposite to the polar diameter change of the curved arc segment of the second screw 220.

It should be noted that, as shown in Figure 4, for the first screw 210, the value of the center angle of the arc segment can be determined according to actual conditions or by gradual adjustment in geometric modeling. In this regard, the embodiment of the present application does not limit the center angle of the first screw 210, and only needs to meet the above requirements.

It can be understood that the number of arc segments and curved segments of the second screw 220 is respectively set to k times the number of arc segments and curved segments corresponding to the first screw 210, and the curved segments of the second screw 220 correspond to the polar diameter ρ(θ ₁ )=r+(Rr)θ ₁ /β ₁ , where θ ₁ is the central angle corresponding to the curved segments of the second screw 220, R is the top diameter, and r is the root diameter; β ₁ is the maximum value of θ ₁ , and β ₁ is the maximum central angle of the curved segments of the first screw 210.

The central angle of the arc segment of the second screw rod 220 is 1/2 of the central angle of the arc segment of the first screw rod 210.

k is the rotation speed ratio of the first screw 210 to the second screw 220 .

It should be noted that _β1 is the maximum central angle β of the curved arc segment of the first screw 210.

The central angle of the arc segment of the second screw 220 is 1/2 of the central angle of the arc segment of the first screw 210.

When , the sum of the maximum center angle _β1 of the arc segments of the m second screws 220 connected in sequence and the center angles corresponding to the curved arc segments of the m second screws 220 is π, where m is half of the number of arc segments of the second screw 220. Exemplarily, assuming that the arc segments and the curved arc segments of the first screw 210 are both set to 2, and the speed ratio k is set to 2, then as shown in FIG. 4 and FIG. 5, the arc segments and the curved arc segments of the second screw 220 are respectively set to 4 segments, where the arc segments are A1B1, C1D1, E1F1, and G1H1, and the curved arc segments are A1C1, D1E1, F1G1, and H1B1. Wherein, the center angles of the arc segments are

The maximum central angle of the curve segment is β ₁ , that is

That is, for any arc segment of the second screw 220, ρ(θ ₁ )=r+(Rr)θ ₁ /β ₁ is satisfied.

Among them, O1D1 is R, O1A1 is r, and O1F1 is r.

It is understandable that the top diameters of the first screw 210 and the second screw 220 are both tangent to the inner wall of the barrel 100 .

It should be noted that the top diameters of the first screw 210 and the second screw 220 are tangent to the inner wall of the barrel 100. At this time, the first screw 210 and the second screw 220 can produce a wedge-shaped decompression effect with the side wall of the barrel 100 at the meshing point. As the screws rotate, a periodic tensile force field is introduced to enhance the dispersion mixing and accelerated melting of the multiphase system materials.

It can be understood that the barrel 100 is sequentially provided with a conveying section 110, a melting section 120, a venting section 130 and a mixing and extruding section 140, and the first screw 210 and the second screw 220 both penetrate the conveying section 110, the melting section 120, the venting section 130 and the mixing and extruding section 140; the first screw 210 and the second screw 220 are both provided with a kneading structure 250, and the kneading structure 250 is located in the melting section 120.

It should be noted that, as shown in FIG. 7 , the use of a kneading block structure can increase the effect of the stretching force field.

It should be noted that, as shown in FIG. 6 , a feed port 111 is provided at one end of the conveying section 110 away from the melting section 120, a discharge port 141 is provided at one end of the mixing and extruding section 140 away from the exhaust section 130, and an exhaust port 131 is provided at the exhaust section 130. In the conveying section 110, the first screw 210 and the second screw 220 rotate in the same direction along their respective screw axes, respectively, and a conveying force is generated through friction and positive displacement. The material moves toward the melting section 120 under the combined action of the positive displacement conveying force and the friction between the two screws. In the melting section 120, the barrel 100 melts the material by external heating. At the same time, the meshing point is located on the connecting line of the two screws, resulting in the maximum speed difference, which strengthens the shear mixing effect in the meshing zone, provides more homoclinic orbit points to initiate chaotic mixing, and the kneading structure 250 increases the tensile field effect, thereby enhancing the mixing and melting efficiency. In the exhaust section 130, since the meshing area is located in the plane formed by the axes of the two screws, the relative speed difference of the two screws in the meshing area reaches the maximum, which produces a greater tumbling effect on the material, accelerates the exhaust efficiency, and makes the exhaust gas discharged from the exhaust port 131. In the mixing and extruding section 140, the first screw 210 and the second screw 220 mesh and run in the same direction, so that the first screw 210 and the second screw 220 have better pressure building capacity and extrusion characteristics. At the same time, under the action of the enhanced mixing mechanism described in the melting section 120, the mixing and plasticizing effect is enhanced, so that the material that has become a melt can be stably extruded from the discharge port 141.

It is understandable that the first screw 210 and the second screw 220 are located in the exhaust section 130 and are configured as a large lead structure.

It should be noted that by setting a large lead structure to generate a negative pressure space, the exhaust efficiency can be further improved. It should be noted that the large lead structure means that the spacing between two adjacent threads on the same screw is larger than that of other segments. The specific structure of the large lead is not limited in this application, and those skilled in the art can set it according to actual needs.

1 , 3 to 6 , 8 and 9 , two extruders according to an embodiment of the present application are described. Taking an extruder shown in FIGS. 1 , 3 to 6 , in which the speed ratio of the first screw 210 to the second screw 220 is 2 as an example, the extruder includes a barrel 100 and a screw assembly, the screw assembly includes a first screw 210 and two second screws 220, the first screw 210 and the second screw 220 are meshed and the meshing point is located in the plane formed by the rotation axis 230 of the first screw 210 and the second screw 220, and the top diameter and the root diameter of the first screw 210 are respectively meshed with the root diameter and the top diameter of the second screw 220 to form a broken line 240 connected by continuous Z-shaped line segments as shown in FIG. 3 . As shown in FIG1 , the number of heads of the second screw 220 is set to 2, the top diameter and root diameter of the first screw 210 are respectively the same as the root diameter and top diameter of the second screw 220, and as shown in FIG6 , the first screw 210 and the second screw 220 are both tangent to the inner wall of the barrel 100. At this time, as shown in FIG4 and FIG5 , for any meshing point, the cross section corresponding to the first screw 210 is composed of two circular arc segments (AB and CD) and two curved arc segments (AD and BC) staggered and connected, wherein the circular arc segment AB and the circular arc segment CD correspond to the top diameter R and the root diameter r, respectively. For the curved arc segment AD, it is rotated clockwise with OA as the starting point to determine the central angle θ, and for the curved arc segment BD, it is rotated counterclockwise with OB as the starting point to determine the central angle θ. At this time, the polar diameters corresponding to the central angles all satisfy the polar diameters.

Wherein, k is 2. Correspondingly, for the second screw 220, the cross section meshing with the first screw 210 in FIG4 is composed of 4 arc segments (A1B1, C1D1, E1F1, G1H1) and 4 curved arc segments (A1C1, D1E1, F1G1, H1B1), wherein the arc segment E1F1 meshes with the arc segment AB, and the arc segment E1F1 corresponds to the root diameter r, and the polar diameter corresponding to the central angle θ ₁ of the curved arc segment between two adjacent arc segments satisfies ρ(θ ₁ )＝r+(Rr)θ ₁ /β ₁ , wherein,

Wherein, k is 2. At this time, referring to FIG. 6 , in the conveying section 110 , the first screw 210 and the second screw 220 rotate in the same direction along their respective rotation axes 230 , and generate a conveying force through friction and positive displacement; the material moves toward the melting section 120 under the combined action of the positive displacement conveying force and the friction between the two screws. In the melting section 120 , the barrel 100 melts the material by external heating. At the same time, the meshing point is located on the connecting line of the two screws so that the maximum speed difference can be generated at the meshing point, strengthening the shear mixing effect in the meshing area, and providing more homoclinic orbital points to initiate chaotic mixing, thereby enhancing mixing and melting efficiency. The material eventually becomes a melt under the action of external heating and the screw mechanism, and then enters the exhaust section 130 under the push of the first screw 210 and the second screw 220 . In the exhaust section 130, the first screw 210 and the second screw 220 adopt a large lead structure to generate a negative pressure space. Since the meshing area is located in the plane formed by the axes of the two screws, the relative speed difference of the two screws in the meshing area reaches the maximum, which produces a greater tumbling effect on the material, accelerates the exhaust efficiency, and makes the exhaust gas discharged from the exhaust port 131. At the same time, the first screw 210 and the second screw 220 drive the material to enter the mixing and extrusion section 140. In the mixing and extrusion section 140, the first screw 210 and the second screw 220 mesh and operate in the same direction, so that the first screw 210 and the second screw 220 have better pressure building capacity and extrusion characteristics. At the same time, under the action of the enhanced mixing mechanism described in the melting section 120, the mixing and plasticizing effect is enhanced, so that the material that has become a melt can be stably extruded from the discharge port 141.

For the extruder in which the speed ratio of the first screw 210 and the second screw 220 is 1, since the extruder described above is mainly different from the above-described extruder in the arrangement of the arc segments and the curved segments on the cross section, only the difference is described here. At this time, referring to Figures 8 and 9 in combination with Figures 1 and 6, it can be seen that for any meshing point, the cross section corresponding to the first screw 210 and the second screw 220 is composed of 2 arc segments and 2 curved segments staggered in connection, wherein, for the first screw 210, the arc segment AB and the arc segment DC correspond to the top diameter R and the root diameter r respectively; for the curved segments BC and AD between the two arc segments of the first screw 210, they both satisfy the extreme diameter

Correspondingly, for the second screw 220, the arc segment E1F1 meshes with the arc segment AB. The arc segment E1F1 corresponds to the root diameter r, and the other arc segment A1B1 corresponds to the top diameter R. The polar diameters corresponding to the curve segments between two adjacent arc segments all satisfy ρ(θ ₁ )=r+(Rr)θ ₁ /β.

It should be noted that when the speed ratio is 2, the meshing effect is best.

As shown in FIG. 10 , the extrusion processing method provided by the present application is applied to the extruder as described above, and the method includes:

Step S100 , obtaining a rotation speed ratio between the first screw 210 and the second screw 220 .

Step S200, controlling the first screw 210 and the second screw 220 to rotate in the same direction at a speed ratio so that the material entering from the inlet of the barrel 100 is transferred to the outlet of the barrel 100 and processed during the transfer process.

Step S300: During the transmission process, the temperature of the melting section 120 of the barrel 100 is monitored in real time.

Step S400: determining whether to adjust the heating power of the heating device disposed in the melting section 120 according to the result of the temperature monitoring.

The preferred embodiments of the present application are described above with reference to the accompanying drawings, but the scope of the rights of the present application is not limited thereto. Any modification, equivalent substitution and improvement made by a person skilled in the art without departing from the scope and essence of the present application should be within the scope of the rights of the present application.

Claims

An extruder, characterized in that it comprises:

Barrel;

A screw assembly, the screw assembly comprising a first screw and a plurality of second screws, the first screw and the plurality of second screws all rotate in the same direction and are arranged in the barrel, the first screw and the second screw are meshed and the meshing point is located in the plane formed by the rotation axes of the first screw and the second screw; the top diameter of the first screw and the root diameter of the second screw are meshed at the plane; the root diameter of the first screw and the top diameter of the second screw are meshed at the plane.
The extruder according to claim 1 is characterized in that the head ratio of the second screw to the first screw is inversely proportional to the speed ratio of the first screw to the second screw.
The extruder according to claim 1, characterized in that

The top diameter of the first screw is the same as the top diameter of the second screw, and the root diameter of the first screw is the same as the root diameter of the second screw.
The extruder according to claim 3, characterized in that

The cross-sections of the first screw and the second screw corresponding to each meshing point are composed of an even number of circular arc segments and an even number of curved arc segments staggered together, and the radii of the circles corresponding to two adjacent circular arc segments are the root diameter and the top diameter, respectively; each of the curved arc segments on the same screw cross-section is a curved arc whose central angle changes linearly and at the same rate of change, and the two meshing cross-sections are symmetrically arranged along the line connecting the corresponding two rotation centers.
The extruder according to claim 4, characterized in that

The polar diameter corresponding to the curved arc segment of the first screw
Wherein θ is the central angle corresponding to the curved arc segment of the first screw, R is the top diameter, and r is the root diameter; k is the speed ratio of the first screw to the second screw; β is the maximum value of θ and the sum of the central angles corresponding to β and the adjacent arc segments is π.
The extruder according to claim 4 or 5, characterized in that

The number of circular arc segments and curved arc segments of the second screw is respectively set to k times the number of circular arc segments and curved arc segments corresponding to the first screw, the polar diameter corresponding to the curved arc segment of the second screw is ρ(θ 1 )=r+(Rr)θ 1 /β 1 , wherein θ 1 is the central angle corresponding to the curved arc segment of the second screw, R is the top diameter, and r is the root diameter; β 1 is the maximum value of θ 1 , and β 1 is the maximum central angle of the curved arc segment of the first screw.
The center angle of the arc segment of the second screw is equal to the center angle of the arc segment of the first screw.
k is the speed ratio of the first screw to the second screw.
The extruder according to claim 1, characterized in that

The top diameters of the first screw and the second screw are both tangent to the inner side wall of the barrel.
The extruder according to claim 1 is characterized in that the barrel is sequentially provided with a conveying section, a melting section, a venting section and a mixing and extrusion section, and the first screw and the second screw both pass through the conveying section, the melting section, the venting section and the mixing and extrusion section; the first screw and the second screw are both provided with a kneading structure, and the kneading structure is located in the melting section.
The extruder according to claim 8 is characterized in that the first screw and the second screw are located in the exhaust section and are configured as a large lead structure.
An extrusion processing method, characterized in that it is applied to the extruder according to any one of claims 1 to 9, and the method comprises:

Obtaining a speed ratio between the first screw and the second screw;

Controlling the first screw and the second screw to rotate in the same direction at the speed ratio so that the material entering from the barrel inlet is transferred to the barrel outlet and processed during the transfer process;

During the transmission process, the melting section of the barrel is monitored in real time for temperature;

Whether to adjust the heating power of the heating device disposed in the melting section is determined according to the result of temperature monitoring.