Screw assembly and screw barrel screw assembly of double-screw extruder

Abstract

The utility model discloses a screw assembly and a screw barrel screw assembly of a double-screw extruder, and belongs to the technical field of plastic processing equipment, the screw assembly comprises two screws which have the same structure and are meshed with each other, and each screw comprises a conveying section, a melting plasticizing section, a mixing section and a metering section which are connected in sequence; the metering section comprises 3-5 forward thread blocks I and 3-5 forward thread blocks II which are connected in sequence; the lead of the first forward threaded block is 40-50 mm, and the length of the first forward threaded block is 40-50 mm. The lead of the second forward threaded block ranges from 30 mm to 38 mm, and the length of the second forward threaded block ranges from 30 mm to 38 mm. The screw assembly disclosed by the utility model can quantitatively, continuously and stably enter a dipping mold, and generates enough pressure to enter the dipping mold to dip and coat continuous fibers, so that the pressure and the conveying of a melt are stable, the melt is uniformly distributed in the dipping mold, and the thickness difference of a product is effectively controlled.

Description

Technical Field

[0001] The utility model relates to the technical field of plastic processing equipment, in particular to a screw combination and a barrel screw combination of a twin-screw extruder. Background Art

[0002] In recent years, with the development of high-performance, high-temperature resistant thermoplastic resins and the continuous maturity of composite material molding and processing technology, thermoplastic composite materials have become the most eye-catching research and development hotspot in the field of composite materials. Continuous fiber reinforced thermoplastic composites have been widely used in many fields such as automotive industry, aerospace, military industry, electronics, etc. due to their light weight, high stiffness, high toughness, and recyclability.

[0003] High-performance continuous fiber reinforced thermoplastic composites have extremely high requirements on the impregnation effect, ash content and thickness uniformity of the primary product unidirectional prepreg tape. This requires that the twin-screw extruder in the continuous fiber unidirectional prepreg tape production line can continuously and stably deliver thermoplastic melt with stable melt pressure to the impregnation mold during the production process.

[0004] The existing production lines designed and manufactured by unidirectional prepreg equipment manufacturers, as well as the unidirectional prepreg production lines designed by continuous fiber reinforced thermoplastic composite material providers themselves, all rely on melt pumps to solve the problem of melt pressure building and transportation. However, melt pumps consume a lot of energy, and there is a risk of temperature and speed being out of control, which affects the stability of melt temperature and pressure, and thus the impregnation effect. At the same time, there are inevitably dead corners in the melt pump, and the heat retention of materials in the dead corners will cause yellowing and carbonization, which will cause stains and black spots on the tape.

[0005] In view of this, this application is filed. Utility Model Content

[0006] The purpose of the utility model is to overcome the shortcomings of the prior art and provide a screw combination and a barrel-screw combination of a twin-screw extruder, which can quantitatively, continuously and stably enter the impregnation mold, generate sufficient pressure to enter the impregnation mold to impregnate and coat the continuous fibers, stabilize the pressure and conveying of the melt, evenly distribute the melt in the impregnation mold, and effectively control the thickness difference of the product.

[0007] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0008] A screw assembly of a twin-screw extruder, the screw assembly comprising two screws of the same structure and meshing with each other, the screw comprising a conveying section, a melting and plasticizing section, a mixing section and a metering section connected in sequence;

[0009] The metering section includes 3 to 5 positive thread blocks 1 and 3 to 5 positive thread blocks 2 connected in sequence;

[0010] The lead of the forward thread block 1 is 40-50 mm and the length is 40-50 mm;

[0011] The lead of the second forward thread block is 30-38 mm and the length is 30-38 mm.

[0012] Preferably, the metering section further comprises a gasket, and the gasket is located between the mixing section and the forward thread block 1.

[0013] Preferably, the conveying section comprises 1 forward thread block 1, 2 to 4 forward thread blocks 3, and 1 forward thread block 4 connected in sequence;

[0014] The lead of the forward thread block 3 is 70-80 mm and the length is 70-80 mm;

[0015] The lead of the forward thread block 4 is 60-68 mm and the length is 60-68 mm.

[0016] Preferably, the melt plasticizing section comprises 1 forward thread block 1, 2 to 3 forward kneading blocks 1, 1 forward kneading block 2, 1 forward thread block 1, 1 forward kneading block 1, 1 forward kneading block 3, 1 forward kneading block 2, 1 reverse thread block, and 3 to 5 forward thread blocks 3 connected in sequence;

[0017] The forward kneading block 1 adopts 4 to 6 forward kneading blocks with a staggered angle of 30 to 45 degrees and a length of 40 to 50 mm;

[0018] The forward kneading block 2 uses 4 to 6 forward kneading blocks with a staggered angle of 60 to 90 degrees and a length of 40 to 50 mm;

[0019] The forward kneading block 3 uses 4 to 6 forward kneading blocks with a staggered angle of 30 to 45 degrees and a length of 30 to 38 mm;

[0020] The lead of the reverse thread block is 30-38 mm and the length is 10-20 mm.

[0021] Preferably, the mixing section comprises 2 to 3 forward kneading blocks 1, 2 to 3 forward threaded blocks 1, 1 forward kneading block 3, 1 forward kneading block 1, and 3 to 5 forward threaded blocks 3 connected in sequence.

[0022] Preferably, the length ratio of the conveying section, the melting and plasticizing section, the mixing section and the metering section is (15-25): (20-40): (20-40): (10-20).

[0023] Preferably, the aspect ratio of the screw is (32-48):1.

[0024] The utility model also provides a screw barrel and screw assembly of a twin-screw extruder, comprising a screw barrel assembly and a screw assembly installed in the screw barrel assembly, wherein a feeding port is provided at a position of the screw barrel assembly corresponding to the conveying section, and an exhaust port is provided at a position of the screw barrel assembly corresponding to the melting and plasticizing section;

[0025] The screw assembly is the screw assembly described above.

[0026] Preferably, the barrel assembly comprises 8 to 12 barrel sections.

[0027] Preferably, the length of a single section of the screw barrel is 3 to 5 times the inner diameter of the screw barrel.

[0028] The beneficial effects of the utility model are as follows: the utility model realizes the pressure building and stable delivery of the melt by setting the metering section of the screw combination of the twin-screw extruder to build up pressure and quantitatively deliver the melt, and uses a screw block combination with a specific pitch and length in the screw metering section. The specific metering section of the utility model enables the melt to enter the impregnation mold quantitatively, continuously and stably, and generates sufficient pressure to enter the impregnation mold to impregnate and coat the continuous fibers, so that the pressure and delivery of the melt are stable, the melt is evenly distributed in the impregnation mold, and the thickness difference of the product is effectively controlled; (2) the screw combination of the utility model does not need to be equipped when it is used. The melt pump can effectively eliminate the factors of uneven melt distribution caused by temperature runaway and unstable speed of the melt pump, stabilize the pressure and delivery of the melt, evenly distribute the melt in the impregnation mold, effectively control the thickness difference of the product, and effectively eliminate the yellowing and carbonization problems of materials in the dead corners of the melt pump delivery, and reduce the stains and black spots of the produced unidirectional belt by 10% to 50%; (3) When the screw assembly of the utility model is used, since it does not need to be equipped with a melt pump, it can reduce the construction cost of the production line and has a high economic value. At the same time, it can effectively reduce the power consumption of the production line, reduce the process steps, and reduce the difficulty of operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1-2 It is a schematic diagram of the screw assembly structure of the twin-screw extruder of the utility model.

[0030] Figure 3-4 The utility model is another schematic diagram of the screw assembly structure of the twin-screw extruder.

[0031] Figure 5 The utility model is a schematic diagram of the screw barrel and screw combination structure of the twin-screw extruder.

[0032] Figure 6 This is a schematic diagram of the combined structure of the barrel and screw of another twin-screw extruder of the utility model.

[0033] Markings in the figure: 1, screw; 11, conveying section; 12, melting and plasticizing section; 13, mixing section; 14, metering section; 2, screw-barrel combination; 21, feeding port; 22, exhaust port. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0035] It should be noted that in this application:

[0036] 48 / 48A indicates a positive thread block with a lead of 48mm and a length of 48mm. The A in 48 / 48A indicates that the thread block is the starting element of the screw, and the other data are similar.

[0037] 48 / 48 means a positive thread block with a lead of 48mm and a length of 48mm, and the other data are similar.

[0038] 32 / 16L means a reverse thread block with a lead of 32mm and a length of 16mm, and the other data are similar.

[0039] 45° / 5 / 48 means 5 forward kneading blocks with a length of 48 mm and a staggered angle of 45°, and other data can be deduced by analogy, wherein the staggered angle represents the staggered angle of adjacent kneading blocks.

[0040] G10-CTH indicates a gasket.

[0041] The CTH in 48 / 48-CTH stands for a triple-start threaded component, and the other data are similar.

[0042] The threaded block and kneading block of the present application are conventional commercially available products.

[0043] See also Figure 1 to Figure 4 The utility model provides a screw assembly of a twin-screw extruder, the screw assembly comprises two screws 1 of the same structure and meshing with each other, the screw 1 comprises a conveying section 11, a melting and plasticizing section 12, a mixing section 13 and a metering section 14 which are connected in sequence;

[0044] The metering section 14 includes 3 to 5 positive thread blocks 1 and 3 to 5 positive thread blocks 2 connected in sequence;

[0045] The lead of the forward thread block 1 is 40-50 mm and the length is 40-50 mm;

[0046] The lead of the second forward thread block is 30-38 mm and the length is 30-38 mm.

[0047] The utility model creatively arranges the metering section 14 of the screw combination of the twin-screw extruder to have the function of building up pressure and quantitatively conveying the melt. By using a screw block combination with a specific lead and length in the screw metering section 14, the pressure building and stable conveying of the melt are achieved. The specific metering section 14 of the utility model can enable the melt to enter the impregnation mold quantitatively, continuously and stably, generate sufficient pressure to enter the impregnation mold to impregnate and coat the continuous fibers, stabilize the pressure and conveying of the melt, and evenly distribute the melt in the impregnation mold, effectively controlling the thickness difference of the product.

[0048] The thread combination of the utility model is suitable for preparing modified thermoplastic resin or thermoplastic resin related products, wherein the thermoplastic resin includes thermoplastic resins such as PP, PE, PA, PC, PET, ABS, etc.

[0049] The screw assembly of the utility model is particularly suitable for preparing continuous fiber reinforced thermoplastic resin tapes, continuous fiber reinforced thermoplastic composite materials, continuous fiber reinforced thermoplastic sheets, and continuous fiber reinforced thermoplastic resin unidirectional prepreg tapes, wherein the continuous fibers include continuous fibers such as glass fibers, carbon fibers, aramid fibers, basalt fibers, or silicon carbide fibers.

[0050] Exemplarily, the content of continuous fibers in the continuous fiber reinforced thermoplastic resin tape is 20 to 80 wt %.

[0051] When the screw assembly of the utility model is used, it does not need to be equipped with a melt pump, and can effectively eliminate the factors of uneven melt distribution caused by temperature runaway and unstable speed of the melt pump, so that the pressure and transportation of the melt are stable, the melt is evenly distributed in the impregnation mold, and the thickness difference of the product is effectively controlled. At the same time, it can effectively eliminate the yellowing and carbonization problems of materials in the dead corners of the melt pump transportation, and the stains and black spots of the produced unidirectional belts are reduced by 10% to 50%.

[0052] When the screw assembly of the utility model is used, since it does not need to be equipped with a melt pump, it can reduce the construction cost of the production line and has a high economic value. At the same time, it can effectively reduce the power consumption of the production line, reduce the process steps, and reduce the difficulty of operation.

[0053] In one embodiment, the metering section 14 includes four positive thread blocks one and four positive thread blocks two connected in sequence;

[0054] The lead of the forward thread block 1 is 48 mm and the length is 48 mm;

[0055] The lead of the forward thread block 2 is 32 mm and the length is 32 mm.

[0056] In one embodiment, the metering section 14 includes three positive thread blocks one and five positive thread blocks two connected in sequence;

[0057] The lead of the forward thread block 1 is 48 mm and the length is 48 mm;

[0058] The lead of the forward thread block 2 is 32 mm and the length is 32 mm.

[0059] In one embodiment, the metering section 14 further includes a gasket, and the gasket is located between the mixing section 13 and the forward thread block 1.

[0060] In one embodiment, when the metering section 14 further includes a gasket, the metering section 14 is a gasket, 3 to 5 positive thread blocks 1, and 3 to 5 positive thread blocks 2 that are connected in sequence.

[0061] Exemplarily, the metering section 14 includes a gasket, three positive thread blocks one, and five positive thread blocks two connected in sequence.

[0062] In one embodiment, the conveying section 11 includes 1 forward thread block 1, 2 to 4 forward thread blocks 3, and 1 forward thread block 4 connected in sequence;

[0063] The lead of the forward thread block 3 is 70-80 mm and the length is 70-80 mm;

[0064] The lead of the forward thread block 4 is 60-68 mm and the length is 60-68 mm.

[0065] In one embodiment, the conveying section 11 includes 1 forward thread block 1, 3 forward thread blocks 3, and 1 forward thread block 4 connected in sequence;

[0066] The lead of the forward thread block 3 is 72 mm and the length is 72 mm;

[0067] The lead of the forward thread block 4 is 64 mm and the length is 64 mm.

[0068] The conveying section 11 of the utility model is mainly used to smoothly convey all materials to the next section for melting and plasticization.

[0069] In one embodiment, the melt plasticizing section 12 includes 1 forward thread block 1, 2 to 3 forward kneading blocks 1, 1 forward kneading block 2, 1 forward thread block 1, 1 forward kneading block 1, 1 forward kneading block 3, 1 forward kneading block 2, 1 reverse thread block, and 3 to 5 forward thread blocks 3 connected in sequence;

[0070] The forward kneading block 1 adopts 4 to 6 forward kneading blocks with a staggered angle of 30 to 45 degrees and a length of 40 to 50 mm;

[0071] The forward kneading block 2 uses 4 to 6 forward kneading blocks with a staggered angle of 60 to 90 degrees and a length of 40 to 50 mm;

[0072] The forward kneading block 3 uses 4 to 6 forward kneading blocks with a staggered angle of 30 to 45 degrees and a length of 30 to 38 mm;

[0073] The lead of the reverse thread block is 30-38 mm and the length is 10-20 mm.

[0074] The melting and plasticizing section 12 of the utility model mainly functions to transform the raw materials from a mixture of various particles and powders into a melt.

[0075] In one embodiment, the melt plasticizing section 12 includes 1 forward thread block 1, 2 forward kneading blocks 1, 1 forward kneading block 2, 1 forward thread block 1, 1 forward kneading block 1, 1 forward kneading block 3, 1 forward kneading block 2, 1 reverse thread block, and 4 forward thread blocks 3 connected in sequence;

[0076] The forward kneading block 1 is a 48 mm long forward kneading block with a staggered angle of 45°;

[0077] The forward kneading block 2 is composed of five forward kneading blocks with a staggered angle of 90° and a length of 48 mm;

[0078] The forward kneading block 3 uses 5 forward kneading blocks with a length of 32 mm and a staggered angle of 45°;

[0079] The reverse thread block has a lead of 32 mm and a length of 16 mm.

[0080] In one embodiment, the mixing section 13 includes 2 to 3 forward kneading blocks 1, 2 to 3 forward threaded blocks 1, 1 forward kneading block 3, 1 forward kneading block 1, and 3 to 5 forward threaded blocks 3 connected in sequence.

[0081] In one embodiment, the mixing section 13 includes two forward kneading blocks 1, two forward screw blocks 1, one forward kneading block 3, one forward kneading block 1, and four forward screw blocks 3 connected in sequence.

[0082] The mixing section 13 of the present invention functions to fully mix the melt and improve the plasticization quality of the melt.

[0083] The melt plasticizing section 12 and the mixing section 13 of the utility model can prolong the melt plasticizing and mixing time of the material, improve the melt plasticizing and mixing effect, and avoid leakage, thereby making the raw materials mixed evenly and the melt mixed fully.

[0084] In one embodiment, the length ratio of the conveying section 11, the melting and plasticizing section 12, the mixing section 13, and the metering section 14 is (15-25): (20-40): (20-40): (10-20).

[0085] Preferably, the aspect ratio of the screw 1 is (32-48):1.

[0086] See also Figure 5-6 The utility model provides a screw barrel and screw assembly of a twin-screw extruder, comprising a screw barrel assembly 2 and a screw assembly installed in the screw barrel assembly, wherein a feeding port 21 is provided at a position corresponding to a conveying section 11 of the screw barrel assembly 2, and an exhaust port 22 is provided at a position corresponding to a melting and plasticizing section 12 of the screw barrel assembly 2;

[0087] The screw assembly is the screw assembly described above.

[0088] In one embodiment, the barrel assembly includes 8 to 12 barrel sections.

[0089] It should be noted that the number of sections of the screw barrel can be designed to be 8 to 12 sections according to actual needs, as long as the length of all the screw barrel assemblies 2 corresponds to the screw rod assembly.

[0090] In one embodiment, the length of a single section of the barrel is 3 to 5 times the inner diameter of the barrel.

[0091] In one embodiment, the length of a single section of the barrel is 4 times the inner diameter of the barrel.

[0092] The following examples are provided to facilitate understanding of the present invention. These examples are not provided to limit the scope of the claims.

[0093] Example 1

[0094] See also Figure 1-2 This embodiment provides a screw assembly of a twin-screw extruder, wherein the screw assembly includes two screws 1 of identical structure and meshing with each other, wherein the screw 1 includes a conveying section 11, a melting and plasticizing section 12, a mixing section 13 and a metering section 14 connected in sequence.

[0095] The conveying section 11 includes 48 / 48A, 72 / 72, 72 / 72, 72 / 72, 64 / 64 connected in sequence.

[0096] Among them, the melt plasticization section 12 includes 48 / 48, 45° / 5 / 48, 45° / 5 / 48, 90° / 5 / 48, 48 / 48, 45° / 5 / 48, 45° / 5 / 32, 90° / 5 / 48, 32 / 16L, 72 / 72, 72 / 72, 72 / 72, and 72 / 72 connected in sequence.

[0097] Wherein, the mixing section 13 includes 45° / 5 / 48, 45° / 5 / 48, 48 / 48, 48 / 48, 45° / 5 / 32, 45° / 5 / 48, 32 / 16L, 72 / 72, 72 / 72, 72 / 72, 72 / 72, connected in sequence.

[0098] Wherein, the metering section includes 48 / 48, 48 / 48, 48 / 48, 48 / 48, 32 / 32, 32 / 32, 32 / 32, 32 / 32 connected in sequence.

[0099] Wherein, the length ratio of the conveying section 11, the melting and plasticizing section 12, the mixing section 13, and the metering section 14 is 20:34:30:16.

[0100] Wherein, the aspect ratio of the screw 1 is 40:1.

[0101] Example 2

[0102] See also Figure 3-4 This embodiment provides a screw assembly of a twin-screw extruder, wherein the screw assembly includes two screws 1 of identical structure and meshing with each other, wherein the screw 1 includes a conveying section 11, a melting and plasticizing section 12, a mixing section 13 and a metering section 14 connected in sequence.

[0103] The conveying section 11 includes 48 / 48A, 72 / 72, 72 / 72, 72 / 72, 64 / 64 connected in sequence.

[0104] Among them, the melt plasticization section 12 includes 48 / 48, 45° / 5 / 48, 45° / 5 / 48, 90° / 5 / 48, 48 / 48, 45° / 5 / 48, 45° / 5 / 32, 90° / 5 / 48, 32 / 16L, 72 / 72, 72 / 72, 72 / 72, and 72 / 72 connected in sequence.

[0105] Wherein, the mixing section 13 includes 45° / 5 / 48, 45° / 5 / 48, 48 / 48, 48 / 48, 45° / 5 / 32, 45° / 5 / 48, 32 / 16L, 72 / 72, 72 / 72, 72 / 72, 72 / 72, connected in sequence.

[0106] Wherein, the metering section includes G10-CTH, 48 / 48-CTH, 48 / 48-CTH, 48 / 48-CTH, 32 / 32-CTH, 32 / 32-CTH, 32 / 32-CTH, 32 / 32-CTH, 32 / 32-CTH, 32 / 32-CTH connected in sequence.

[0107] Wherein, the length ratio of the conveying section 11, the melting and plasticizing section 12, the mixing section 13, and the metering section 14 is 20:34:30:16.

[0108] Wherein, the aspect ratio of the screw 1 is 40:1.

[0109] Example 3

[0110] See also Figure 5 This embodiment provides a screw barrel and screw assembly of a twin-screw extruder, including a screw barrel assembly 2 and a screw assembly installed in the screw barrel assembly, wherein a feeding port 21 is provided at a position corresponding to the conveying section 11 of the screw barrel assembly 2, and an exhaust port 22 is provided at a position corresponding to the melting and plasticizing section 12 of the screw barrel assembly 2;

[0111] Wherein, the screw combination is the screw combination of Example 1.

[0112] The barrel assembly includes 10 barrel sections, the feed port 21 is located at the first barrel section, the exhaust port 22 is located at the fifth barrel section, and the length of a single barrel section is 4 times the inner diameter of the barrel.

[0113] The preparation of continuous fiber reinforced thermoplastic resin unidirectional prepreg tape is used to exemplarily illustrate the steps of the barrel screw combination of the twin-screw extruder of this embodiment in preparing related products:

[0114] Step 1: The mixed raw materials enter through the first section of the screw barrel, and are melted and plasticized by the screw assembly between the second to seventh sections of the screw barrel, and the raw materials are transformed from a mixture of particles and powders into a flowing melt.

[0115] Step 2: After the melt is pressurized by the small-pitch double-start or triple-start threaded element of the metering section of the screw assembly, it enters the impregnation mold of the subsequent process step through the connector between the barrel and the mold.

[0116] Step 3: The melt that has completed the pressure build-up completes the impregnation and coating of the continuous fiber in the impregnation mold.

[0117] Example 4

[0118] See also Figure 6This embodiment provides a screw barrel and screw assembly of a twin-screw extruder, including a screw barrel assembly 2 and a screw assembly installed in the screw barrel assembly, wherein a feeding port 21 is provided at a position of the screw barrel assembly 2 corresponding to the conveying section 11, and an exhaust port 22 is provided at a position of the screw barrel assembly 2 corresponding to the melting and plasticizing section 12;

[0119] Wherein, the screw combination is the screw combination of Example 2.

[0120] The barrel assembly includes 10 barrel sections, the feed port 21 is located at the first barrel section, the exhaust port 22 is located at the fifth barrel section, and the length of a single barrel section is 4 times the inner diameter of the barrel.

[0121] The preparation of continuous fiber reinforced thermoplastic resin unidirectional prepreg tape is used to exemplarily illustrate the steps of the barrel screw combination of the twin-screw extruder of this embodiment in preparing related products:

[0122] Step 1: The mixed raw materials enter through the first section of the screw barrel, and are melted and plasticized by the screw assembly between the second to seventh sections of the screw barrel, and the raw materials are transformed from a mixture of particles and powders into a flowing melt.

[0123] Step 2: After the melt is pressurized by the small-pitch double-start or triple-start threaded element of the metering section of the screw assembly, it enters the impregnation mold of the subsequent process step through the connector between the barrel and the mold.

[0124] Step 3: The melt that has completed the pressure build-up completes the impregnation and coating of the continuous fiber in the impregnation mold.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit the protection scope of the utility model. Although the utility model is described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the utility model.

Claims

1. A screw assembly of a twin-screw extruder, characterized in that: The screw assembly comprises two screws of the same structure and meshing with each other, and the screw comprises a conveying section, a melting and plasticizing section, a mixing section and a metering section which are connected in sequence; The metering section includes 3 to 5 positive thread blocks 1 and 3 to 5 positive thread blocks 2 connected in sequence; The lead of the forward thread block 1 is 40-50 mm and the length is 40-50 mm; The lead of the second forward thread block is 30-38 mm and the length is 30-38 mm.

2. The screw assembly of the twin-screw extruder according to claim 1, characterized in that: The metering section also includes a gasket, which is located between the mixing section and the forward thread block.

3. The screw assembly of the twin-screw extruder according to claim 1, characterized in that: The conveying section includes one positive thread block one, 2 to 4 positive thread blocks three, and one positive thread block four which are connected in sequence; The lead of the forward thread block 3 is 70-80 mm and the length is 70-80 mm; The lead of the forward thread block 4 is 60-68 mm and the length is 60-68 mm.

4. The screw assembly of a twin-screw extruder according to any one of claims 1 to 3, characterized in that: The melt plasticizing section comprises 1 forward thread block 1, 2-3 forward kneading blocks 1, 1 forward kneading block 2, 1 forward thread block 1, 1 forward kneading block 1, 1 forward kneading block 3, 1 forward kneading block 2, 1 reverse thread block, and 3-5 forward thread blocks 3 connected in sequence; The forward kneading block 1 adopts 4 to 6 forward kneading blocks with a staggered angle of 30 to 45 degrees and a length of 40 to 50 mm; The forward kneading block 2 uses 4 to 6 forward kneading blocks with a staggered angle of 60 to 90 degrees and a length of 40 to 50 mm; The forward kneading block 3 uses 4 to 6 forward kneading blocks with a staggered angle of 30 to 45 degrees and a length of 30 to 38 mm; The lead of the reverse thread block is 30-38 mm and the length is 10-20 mm.

5. The screw assembly of the twin-screw extruder according to claim 4, characterized in that: The mixing section includes 2 to 3 forward kneading blocks one, 2 to 3 forward threaded blocks one, 1 forward kneading block three, 1 forward kneading block one, and 3 to 5 forward threaded blocks three which are connected in sequence.

6. The screw assembly of the twin-screw extruder according to claim 1, characterized in that: The length ratio of the conveying section, the melting and plasticizing section, the mixing section and the metering section is (15-25): (20-40): (20-40): (10-20).

7. The screw assembly of the twin-screw extruder according to claim 1, characterized in that: The aspect ratio of the screw is (32-48):

1.

8. A barrel-screw combination of a twin-screw extruder, characterized in that: It comprises a barrel assembly and a screw assembly installed in the barrel assembly, wherein a feeding port is provided at a position of the barrel assembly corresponding to the conveying section, and an exhaust port is provided at a position of the barrel assembly corresponding to the melting and plasticizing section; The screw assembly is the screw assembly described in any one of claims 1 to 7.

9. The barrel-screw combination of a twin-screw extruder according to claim 8, characterized in that: The screw barrel combination comprises 8 to 12 sections of screw barrels.

10. The barrel-screw assembly of a twin-screw extruder according to claim 9, characterized in that: The length of the single-section screw barrel is 3 to 5 times the inner diameter of the screw barrel.

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