CN110315735A - Based on oval cross section and the periodically variable plasticizing rotor of lift angle - Google Patents

Abstract

The invention discloses a plasticizing rotor based on elliptical section and periodic change of lift angle, which includes one or two rotors, each rotor includes a rotor functional structure, and the rotor functional structure includes a conveying section and a plasticizing section , vacuum section, secondary plasticizing section and homogenizing section, the helix angle of the helical structure corresponding to the conveying section, plasticizing section, vacuum section, secondary plasticizing section and homogenizing section at any position in the axial direction is different. The invention creates a brand-new plastic plasticizing rotor. The radial section of the rotor is elliptical, and the axial helix angle changes periodically, so that when the plastic is plasticized in the rotor, the volume changes alternately, and the melt produces stretching/compression effects. , to realize the plastic plasticization process dominated by extensional rheology.

Description

Plasticizing rotor based on elliptical section and periodic variation of lift angle

technical field

The invention relates to the field of plastic product production equipment, in particular to a plasticizing rotor based on periodic changes in elliptical cross-section and lift angle.

Background technique

During the processing and molding of plastic products, the prepared powder or granular plastic is first fed into the barrel, and then conveyed, dispersed, compressed and plasticized by the screw in the barrel. With the assistance of external heating, the barrel The plastic inside changes from solid state to high temperature molten state melt. The melt passes through a shaping mold and can be formed into products of different shapes. In this series of processes, the structure of the screw determines the conveying, dispersion, compression and plasticization of the plastic, that is, the structure of the screw determines the physical properties, appearance and production output of the plastic product. At present, the helix angle of the screw in the same functional section of the plastic processing equipment does not change, resulting in a monotonous and poor plasticization process, and the dispersion is simple and uneven.

In actual production, the screw whose helix angle does not change in the same functional section has the following disadvantages: 1. The fixed helix angle leads to limited plastic dispersion ability and poor dispersion uniformity. 2. The plasticizing ability is weak, and a large amount of external heat energy or a long aspect ratio is required to plasticize the plastic. 3. It is impossible to fully disentangle the molecular chains of polymer materials, so it is difficult to improve the physical properties of plastic products.

The present invention designs a plasticizing rotor based on an elliptical cross-section and periodic lift angle changes. When the rotor is conjugated and rotated in different directions, the overall positive displacement of the plastic is conveyed, because the helix angle of the rotor changes every moment. , when the rise angle becomes larger, the volume of the spiral groove increases, and the plastic presents the effect of stretching, and when the rise angle becomes smaller, the volume of the spiral groove decreases, showing the effect of compression. The continuous stretching/compression of the plastic between the barrel and the rotor changes alternately, making the melt plasticized better and dispersed more uniformly under the condition of extensional rheology. Thereby improving the physical properties of plastic products and reducing production costs.

Contents of the invention

In order to solve the problems raised in the above-mentioned background technology, the object of the present invention is to provide a plasticizing rotor based on periodic changes in elliptical cross-section and lift angle.

In order to achieve the above object, the technical scheme that the present invention takes is:

The present invention provides a plasticizing rotor based on elliptical cross-section and periodic change of lift angle, including one or two rotors, each rotor includes a rotor functional structure, and the rotor functional structure includes a conveying section, a plasticizing section , vacuum section, secondary plasticizing section and homogenizing section, the helix angle of the helical structure corresponding to the conveying section, plasticizing section, vacuum section, secondary plasticizing section and homogenizing section at any position in the axial direction is different.

In the above technical solution, the helix angles of the spiral structures of the conveying section, the vacuum section and the homogenizing section gradually decrease in the corresponding intervals along the material transport direction, and the plasticizing section and the secondary plasticizing section The helix angle of the helix structure in the corresponding section along the material conveying direction changes periodically and alternately.

In the above technical solution, the spiral structure of the conveying section, the vacuum section and the homogenizing section gradually decreases in helix angle in the axial direction from 90 degrees to 0 degrees in the corresponding section along the material transportation direction; wherein, the helix angle is not equal to 90 degrees and 0 degrees.

In the above technical solution, the helical structure of the plasticizing section and the secondary plasticizing section is periodically alternated in a period in which the helix angle in the axial direction decreases from 90 degrees to 0 degrees and then increases to 90 degrees in the corresponding section along the material transportation direction. Change, or the helical structure of the plasticizing section and the secondary plasticizing section changes periodically and alternately in the axial helix angle of the corresponding interval along the material transport direction from 0° to 90° and then decreasing to 0°; Among them, the helix angle is not equal to 90 degrees and 0 degrees.

In the above technical solution, the cross-sectional shape of the spiral structure corresponding to the conveying section, the plasticizing section, the vacuum section, the secondary plasticizing section and the homogenizing section at any position in the axial direction is elliptical.

In the above technical solution, the outer diameter of the functional structure of the rotor is uniform or gradually decreases along the axial direction.

In the above technical solution, each of the rotors further includes a rotor driving part and an auxiliary part, and the rotor driving part and the auxiliary part are respectively arranged at two ends of the functional structure of the rotor.

In the above technical solution, when there are two rotors, the conveying section, plasticizing section, vacuum section, secondary plasticizing section and homogenizing section corresponding to one rotor are the same as the corresponding conveying section on the other rotor. Section, plasticizing section, vacuum section, secondary plasticizing section and homogenizing section are engaged with each other one by one;

The cross-sectional shapes of the screw functional structures on the two rotors at any position in the axial direction are ovals with the same size and tangent to each other.

In the above technical solution, the center point of the cross-section at any position in the axial direction of each rotor coincides with or deviates from the rotation axis of the rotor itself.

Compared with prior art, the beneficial effect of the present invention is:

When one rotor rotates or the two rotors are conjugated and rotated in different directions, while the plastic is conveyed in a positive displacement, the helix angle of the rotor is changing every moment relative to the barrel and the plastic melt: when the rotor When the helix angle of the helical structure tends to increase, the volume of the helical groove of the rotor helical structure increases at this place, and the plastic presents the effect of stretching; when the helix angle of the rotor helical structure tends to decrease, the helical groove of the rotor The volume of the spiral groove shrinks, showing the effect of compression. The continuous stretching/compression of the plastic between the barrel and the rotor changes alternately, making the melt plasticized better and dispersed more uniformly under the condition of extensional rheology. Thereby improving the physical properties of plastic products and reducing production costs.

The invention creates a brand-new plastic plasticizing rotor. The radial section of the rotor is elliptical, and the axial helix angle changes periodically, so that when the plastic is plasticized in the rotor, the volume changes alternately, and the melt produces stretching/compression effects. , to realize the plastic plasticization process dominated by extensional rheology.

The innovation of the present invention is that: the helical structure of the rotor functional structure of the rotor (including the conveying section, the plasticizing section, the vacuum section, the secondary plasticizing section and the homogenizing section) has different helix angles at any position in the axial direction. Yes, when the helix angle of the rotor helical structure tends to become larger, the volume of the helical groove of the rotor helical structure increases, and the plastic presents a stretching effect; when the helix angle of the rotor helical structure tends to decrease, the The volume of the helical groove of the helical structure at the rotor is reduced, showing the effect of compression. The continuous stretching/compression of the plastic between the barrel and the rotor changes alternately, making the melt plasticized better and dispersed more uniformly under the condition of stretching rheology; thus improving the physical properties of plastic products and reducing production costs.

Description of drawings

Fig. 1 is the structural representation of first kind of embodiment of the present invention;

Fig. 1 a is the sectional view of A-A direction in Fig. 1;

Fig. 2 is the structural representation of the second embodiment of the present invention;

Fig. 2 a is the sectional view of B-B direction in Fig. 2;

Fig. 3 is the structural representation of the third embodiment of the present invention;

Fig. 4 is the structural representation of the fourth embodiment of the present invention;

Fig. 5 is the structural representation of the actual application example of the first embodiment;

Fig. 6 is the structural representation of the practical application example 1 of the second embodiment;

Fig. 7 is a schematic structural diagram of a practical application example of the third embodiment;

Fig. 8 is a schematic structural diagram of a practical application example of the fourth embodiment;

Fig. 9 is a schematic structural diagram of practical application example 2 of the second embodiment;

Explanation of reference signs:

100. Rotor functional structure; 200. Rotor driving part; 300. Auxiliary part;

1. Conveying section; 2. Plasticizing section; 3. Vacuum section; 4. Secondary plasticizing section; 5. Homogenizing section.

Detailed ways

In order to make the technical means, creative features, goals and effects achieved by the present invention easy to understand, the following will further explain how the present invention is implemented in conjunction with the accompanying drawings and specific implementation methods.

In the prior art, the "helix angle" of the helical structure is generally defined as the angle between the tangent of the helix and the plane perpendicular to the axis of the helix on the medium-diameter cylindrical surface.

The present invention provides a plasticizing rotor based on elliptical section and periodic change of lift angle, including one or two rotors, each of which includes a rotor functional structure 100, and the rotor functional structure 100 includes a conveying section 1, Plasticizing section 2, vacuum section 3, secondary plasticizing section 4, and homogenizing section 5, the spirals corresponding to the conveying section 1, plasticizing section 2, vacuum section 3, secondary plasticizing section 4, and homogenizing section 5 The angle of the helix angle of the structure at any position in the axial direction is different.

In the present invention, the spiral structures of the conveying section 1, the vacuum section 3 and the homogenizing section 5 gradually decrease in helix angle in the corresponding section along the material transport direction, and the plasticizing section 2 and the secondary plasticizing section In the helical structure of the chemical section 4, the helix angle in the corresponding section along the direction of material transport changes periodically and alternately. Further, the helical structure of the conveying section 1, the vacuum section 3 and the homogenizing section 5 has an axial helix angle gradually decreasing from 90° to 0° in the corresponding section along the material conveying direction. The helical structure of the plasticizing section 2 and the secondary plasticizing section 4 changes periodically and alternately in the helix angle of the axial helix angle in the corresponding interval along the material conveying direction from 90 degrees to 0 degrees and then to 90 degrees, or The helical structure of the plasticizing section 2 and the secondary plasticizing section 4 changes periodically and alternately in the helix angle of the axial helix angle in the corresponding interval along the material transport direction from 0° to 90° and then decreasing to 0°; , the helix angle is not equal to 90 degrees and 0 degrees.

In the present invention, the cross-sectional shape of the spiral structure corresponding to the conveying section 1, the plasticizing section 2, the vacuum section 3, the secondary plasticizing section 4 and the homogenizing section 5 at any position in the axial direction is elliptical.

In the present invention, the outer diameter of the rotor functional structure 100 is uniform or gradually decreases along the axial direction.

In the present invention, each of the rotors further includes a rotor driving part 200 and an auxiliary part 300 , and the rotor driving part 200 and the auxiliary part 300 are respectively arranged at two ends of the rotor functional structure 100 .

In the present invention, when there are two rotors, the corresponding conveying section 1, plasticizing section 2, vacuum section 3, secondary plasticizing section 4 and homogenizing section 5 on one rotor are the same as those on the other rotor. The corresponding conveying section 1, plasticizing section 2, vacuum section 3, secondary plasticizing section 4 and homogenizing section 5 are engaged with each other in one-to-one correspondence;

The cross-sectional shapes of the screw functional structures 100 on the two rotors at any position in the axial direction are ovals with the same size and tangent to each other.

In the present invention, the center point of the cross-section at any axial position of each rotor coincides with or deviates from the rotation axis of the rotor itself. Specifically, the axial movement track of each rotor is a circular movement or a deflection movement with the rotation axis of the rotor itself as the center line.

Embodiment 1: As shown in FIG. 1 , a plasticizing rotor based on an elliptical section and a periodic change in lift angle provided by this embodiment includes a rotor, which is composed of a rotor functional structure 100 and a rotor functional structure 100 The rotor driving part 200 at both ends is composed of an auxiliary part 300. The rotor driving part 200 is used for connecting with a rotor driving device (not shown in the figure), and the auxiliary part 300 is used for melt output.

Among them, the functional structure of the rotor rod is composed of conveying section 1, plasticizing section 2, vacuum section 3, secondary plasticizing section 4 and homogenizing section 5 along the axial direction, and the conveying section 1, plasticizing section 2, vacuum section 3. The helical structure corresponding to the secondary plasticizing section 4 and the homogenizing section 5 has different helix angles at any position in the axial direction. In this embodiment, the spiral structures of the conveying section 1, the vacuum section 3 and the homogenizing section 5 gradually decrease in helix angle in the corresponding section along the material conveying direction. Specifically, the conveying section 1, The spiral structure of the vacuum section 3 and the homogenization section 5 gradually decreases in the axial helix angle from 90 degrees to 0 degrees in the corresponding section along the material conveying direction; wherein, the helix angle is not equal to 90 degrees and 0 degrees.

In the spiral structure of the plasticizing section 2 and the secondary plasticizing section 4 , the helix angles of the axial helix angles in the corresponding intervals along the material conveying direction change periodically and alternately. In this embodiment, the helical structure of the plasticizing section 2 and the secondary plasticizing section 4 is in a period in which the helix angle of the axial helix angle increases from 0 degrees to 90 degrees and then decreases to 0 degrees in the corresponding section along the material transportation direction Alternate change; Among them, the helix angle is not equal to 90 degrees and 0 degrees.

As shown in Fig. 1a, the cross-sectional shape of the spiral structure corresponding to the conveying section 1, the plasticizing section 2, the vacuum section 3, the secondary plasticizing section 4 and the homogenizing section 5 at any position in the axial direction is elliptical. Wherein, the center point of the cross-section at any position in the axial direction of each rotor coincides with or deviates from the rotation axis of the rotor itself.

In this embodiment, the outer diameters of the screw functional structures on the single screw are equal at any position in the axial direction.

Embodiment 2: As shown in Figure 2, this embodiment provides a plasticizing rotor based on the periodic change of elliptical cross-section and lift angle, including 2 rotors, each of which is composed of a rotor functional structure 100 And the rotor driving part 200 and the auxiliary part 300 which are arranged at both ends of the rotor functional structure 100 are composed. The rotor driving part 200 is used for connecting with the rotor driving device (not shown in the figure), and the auxiliary part 300 is used for melt output.

Among them, the rotor rod functional structure 100 of each rotor is composed of conveying section 1, plasticizing section 2, vacuum section 3, secondary plasticizing section 4 and homogenizing section 5 in the axial direction, and the corresponding conveying section on one rotor Section 1, plasticizing section 2, vacuum section 3, secondary plasticizing section 4 and homogenizing section 5 correspond to the conveying section 1, plasticizing section 2, vacuum section 3, and secondary plasticizing section 4 on the other rotor and the homogenizing segments 5 are engaged with each other in one-to-one correspondence;

The spiral structures corresponding to the conveying section 1, the plasticizing section 2, the vacuum section 3, the secondary plasticizing section 4 and the homogenizing section 5 have different helix angles at any position in the axial direction. In this embodiment, the spiral structures of the conveying section 1, the vacuum section 3 and the homogenizing section 5 gradually decrease in helix angle in the corresponding section along the material conveying direction. Specifically, the conveying section 1, The spiral structure of the vacuum section 3 and the homogenization section 5 gradually decreases in the axial helix angle from 90 degrees to 0 degrees in the corresponding section along the material conveying direction; wherein, the helix angle is not equal to 90 degrees and 0 degrees.

In the spiral structure of the plasticizing section 2 and the secondary plasticizing section 4 , the helix angles of the axial helix angles in the corresponding intervals along the material conveying direction change periodically and alternately. In this embodiment, the helical structure of the plasticizing section 2 and the secondary plasticizing section 4 is in a period in which the helix angle of the axial helix angle increases from 0 degrees to 90 degrees and then decreases to 0 degrees in the corresponding section along the material transportation direction Alternate change; Among them, the helix angle is not equal to 90 degrees and 0 degrees.

As shown in Figure 2a, the corresponding two conveying section 1, plasticizing section 2, vacuum section 3, secondary plasticizing section 4, and homogenizing section 5 in the two rotors correspond to the horizontal position of the helical structure at any position in the axial direction. The cross-sectional shape is two ellipses of equal size and tangent. Wherein, the center point of the cross-section at any position in the axial direction of each rotor coincides with or deviates from the rotation axis of the rotor itself.

In this embodiment, the two rotors are identical in shape, size and structure, and the outer diameter of the functional structure of the screw on each rotor is equal at any position in the axial direction.

Embodiment 3: As shown in FIG. 3 , this embodiment is similar in structure to Embodiment 1, the difference is that in this embodiment, the outer diameters of the rotor functional structures 100 on each rotor decrease successively along the axial direction.

Embodiment 4: As shown in FIG. 4 , the structure of this embodiment is similar to that of Embodiment 2, except that in this embodiment, the outer diameters of the rotor functional structures 100 on each rotor decrease successively along the axial direction.

The working principle of the present invention is as follows:

Under the action of the rotor, the plastic is gradually compressed in the conveying section 1 due to the gradual decrease of the helix angle in the conveying section 1 section, and enters the plasticizing section 2. The helix angle of the plasticizing section 2 alternates periodically and changes irregularly. The plastic is stretched or compressed with the periodic change of the rotor helix angle in the plasticizing section 2. When the helix angle becomes larger, the volume of the screw channel Increase the size of the screw, the smaller the helix angle, the smaller the volume of the screw groove, and the melt will produce a stretching and compressing effect as the volume changes, and the stretching rheological plasticizing condition of the melt will be realized. Due to the positive displacement characteristics of the rotor, the plastic is stretched, pressed and wriggled forward, flowing to the vacuum section 3. The helix angle of vacuum section 3 gradually decreases. After the plastic melt is pumped out of the volatile air by the vacuum pump in the vacuum section 3 section, the volume gradually decreases, and the plastic melt is gradually compacted and enters the secondary plasticizing section 4 section. In the second plasticizing section 4, the helix angle changes periodically and alternately, and the plastic melt is stretched or compressed again. Finally, plasticizing, the dispersed plastic melt enters the 5th section of the homogenization section, and the helix angle gradually decreases in the 5th section of the homogenization section, and the melt is forced out of the barrel in a gradient change.

The plasticizing rotor based on the elliptical section and the periodic change of the lift angle provided by the present invention is the core component of plastic molding processing and can be applied to various plastic processing machines. Some application examples are given below, but the structure and construction method proposed by the present invention are not limited to these applications.

1. Single-rotor extruder with elliptical cross-section and periodic change of lift angle

As shown in Figure 5, it is the application of Example 1 in a single-rotor extruder 400 with elliptical cross-section and periodic change of lift angle: when the plasticizing device adopts a single plasticizing rotor with elliptical cross-section and periodic change of lift angle, Together with other components, it forms a single-rotor plasticizing extruder or injection molding machine. By using the periodic change characteristics of the helix angle of the plasticizing section 2 and the secondary plasticizing section 4 in Figure 1, the plasticization of the plastic inside the barrel is strengthened, so that the plastic melt at the outlet is plasticized uniformly and has better dispersion. .

2. Parallel twin-rotor extruder with elliptical section and periodic change of lift angle

As shown in Figure 6, it is the application of the parallel twin-rotor extruder 500 in the elliptical section and the lift angle of the embodiment 2 that changes periodically: when the plasticizing device adopts two plasticizing rotors with the elliptical section and the lift angle that change periodically , together with other components to form a parallel twin-rotor plasticizing extruder. By using the periodic changes in the helix angle of the plasticizing section 2 and the secondary plasticizing section 4 in Fig. 3, as well as the conjugate ellipse 6 and ellipse 7, a plasticizing method with extensional flow as the main body is formed. When the helix angle of the corresponding screw mechanism in the rotor becomes larger, the volume of the screw groove of the screw mechanism increases; when the helix angle of the corresponding screw mechanism in the rotor becomes smaller, the volume of the screw groove of the screw mechanism decreases, and the melt changes in the volume of the screw groove alternately. Being plasticized, the physical performance indicators of plastic products are greatly improved.

3. Single-rotor extruder with tapered elliptical section and periodic change of lift angle

As shown in Figure 7, it is the application of Embodiment 3 in a single-rotor extruder 600 with a conical elliptical section and a periodically changing lift angle: when the plasticizing device adopts a plasticizing rotor with an elliptical section and a periodically changing lift angle , and the plasticizing rotor with elliptical cross-section and periodic change of lift angle is conical (as shown in Figure 3, the rotor functional structure 100 in the rotor is conical), that is, a conical elliptical cross-section and a periodic change of lift angle are formed Rotor extruder. The plastic is pushed forward layer by layer under the action of the conical rotor. The interval between the plasticizing section 2 and the secondary plasticizing section 4 has a conical shape, elliptical cross-sections of different sizes in the radial direction, and the axial angle of rise changes periodically. The plastic is strongly plasticized in the plasticizing section 2 and the secondary plasticizing section 4 due to the volume change, the rotor is shorter than the traditional screw, and the process temperature is lower, which ensures the quality of plastic products and reduces energy consumption. .

4. Dual-rotor extruder with conical elliptical section and periodic change of lift angle

As shown in Figure 8, it is the application of embodiment 4 in the dual-rotor extruder 700 with a conical elliptical cross-section and a periodically changing lift angle: When the rotors are optimized (as shown in Figure 4, the rotor functional structure 100 in each rotor is conical), it becomes a dual-rotor extruder with a conical elliptical cross-section and a periodically changing lift angle. During the conveying and plasticizing process of plastic in the two rotors, the two conical elliptical cross-sections and the plasticizing rotors whose lift angles change periodically are conjugated to each other, combined with the plasticization of plasticizing section 2 and secondary plasticizing section 4 in Figure 1 Function, the volume of the screw groove of the rotor changes alternately, and the plastic stretches and sometimes compresses with the change of the screw groove volume, and the periodic reciprocating changes greatly improve the quality of plastic products.

5. Rotor injection molding machine with elliptical section and periodic change of lift angle

As shown in Figure 9, it is the application of Embodiment 2 in an injection molding machine 800 with an elliptical cross-section and a periodically changing rotor with a lift angle: when the plasticizing rotor with an elliptical cross-section and a periodically changed lift angle is applied to an injection molding machine, it becomes an elliptical cross-section and a rotor with a periodically changing lift angle. Rotor injection molding machine with periodic change in lift angle, according to the above-mentioned principle of periodic change in lift angle and exchange plasticization of volume, makes the rotor injection molding machine with elliptical cross-section and periodic change in lift angle also have the above advantages, with good plasticization and uniform plasticization , the advantage of low energy consumption.

The actual production results prove that the above-mentioned plasticizing rotor based on the periodic change of the elliptical section and the lift angle makes the phase state of the melt at the outlet of the barrel consistent, and the temperature, viscosity, velocity and pressure of each point inside the melt change uniformly, These factors greatly improve the physical properties and appearance of plastic products. At the same time, because the helix angle between the plasticizing section 2 and the secondary plasticizing section 4 changes periodically, the plastic is dominated by elongational rheological plasticization, which makes the internal thermal stress of the melt more uniform, and the reduction of internal heat makes the melt According to the actual processing temperature, the speed range is wider.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements without departing from the spirit and scope of the technical solution of the present invention shall be covered by the claims of the present invention.

Claims (9)

1. A plasticizing rotor based on an elliptical section and a periodic change in lift angle, comprising 1 or 2 rotors, each of which includes a rotor functional structure (100), characterized in that the rotor functional structure (100 ) includes conveying section (1), plasticizing section (2), vacuum section (3), secondary plasticizing section (4) and homogenizing section (5), and described conveying section (1), plasticizing section (2 ), the vacuum section (3), the secondary plasticizing section (4) and the homogenizing section (5) corresponding to the helical structure have different helix angles at any position in the axial direction. 2. A plasticizing rotor based on an elliptical section and a periodic change in lift angle according to claim 1, characterized in that, the conveying section (1), the vacuum section (3) and the homogenization section (5) The axial helix angles of the helical structure in the corresponding intervals along the material conveying direction are gradually decreasing, and the helical structures of the plasticizing section (2) and the secondary plasticizing section (4) have the same axial helix angles in the corresponding intervals. Periodic alternation. 3. A plasticizing rotor based on an elliptical section and a periodic change in lift angle according to claim 2, characterized in that, the conveying section (1), the vacuum section (3) and the homogenization section (5) The axial helix angle of the helical structure in the corresponding section along the material conveying direction gradually decreases from 90 degrees to 0 degrees; wherein, the helix angle is not equal to 90 degrees and 0 degrees. 4. A plasticizing rotor based on elliptical cross-section and periodic change of lift angle according to claim 2, characterized in that, the spiral structure of the plasticizing section (2) and the secondary plasticizing section (4) is The helix angle of the axial helix angle in the corresponding interval along the material conveying direction decreases from 90 degrees to 0 degrees and then increases to 90 degrees periodically and alternately, or the plasticizing section (2) and the secondary plasticizing section (4) The helical structure in the corresponding section along the material conveying direction has an axial helix angle that increases from 0 degrees to 90 degrees and then decreases to 0 degrees periodically and alternately; wherein, the helix angle is not equal to 90 degrees and 0 degrees. 5. A plasticizing rotor based on elliptical cross-section and periodic change of lift angle according to claim 1, characterized in that, the conveying section (1), plasticizing section (2), vacuum section (3), The cross-sectional shape of the helical structure corresponding to the secondary plasticizing section (4) and the homogenizing section (5) at any position in the axial direction is elliptical. 6. A plasticizing rotor based on an elliptical cross-section and periodic changes in lift angle according to claim 1, characterized in that the outer diameter of the functional structure (100) of the rotor is uniform or gradually decreases along the axial direction. 7. A plasticizing rotor based on an elliptical cross-section and a periodic change in lift angle according to claim 1, wherein each rotor also includes a rotor driving part (200) and an auxiliary part (300), so The rotor driving part (200) and the auxiliary part (300) are respectively arranged at two ends of the rotor functional structure (100). 8. A plasticizing rotor based on an elliptical section and a periodic change in lift angle according to claim 7, characterized in that, when there are two rotors, the corresponding conveying section (1) on one of the rotors , plasticizing section (2), vacuum section (3), secondary plasticizing section (4) and homogenizing section (5) and the corresponding conveying section (1) and plasticizing section (2) on the other rotor , the vacuum section (3), the secondary plasticizing section (4) and the homogenizing section (5) are engaged with each other in one-to-one correspondence; The cross-sectional shapes of the screw functional structures (100) on the two rotors at any position in the axial direction are ovals with the same size and tangent to each other. 9. According to claim 1 or 7, a plasticizing rotor based on elliptical cross-section and periodic change of lift angle, characterized in that the center point of the cross-section at any position in the axial direction of each rotor is consistent with the rotation of the rotor itself The axes are coincident or offset.