A special screw for PLA blown film
By designing a special screw for PLA blown film production with a specific structure, the problems of poor film bubble stability and low production capacity in the PLA blown film process were solved, and the stability and production capacity of the film bubble were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- 宁波金亿精密机械有限公司
- Filing Date
- 2025-10-09
- Publication Date
- 2026-07-31
AI Technical Summary
Existing blown film screws suffer from poor film bubble stability and low production capacity when processing polylactic acid (PLA), failing to meet the requirements of PLA blown film technology.
A PLA blown film screw was designed, including a conveying section, a barrier conveying section, a first mixing section, a shearing section, an extrusion section, and a second mixing section. Through a specific screw structure and component layout, the stability and production capacity of the film bubble are improved.
This technology improves the stability and increases the production capacity of film bubbles in the PLA blown film process, thus meeting the process requirements of PLA blown film.
Smart Images
Figure CN224576149U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of screws, and in particular to a screw specifically for PLA blown film. Background Technology
[0002] Polylactic acid (PLA), as a bio-based biodegradable material, is widely used in food packaging, agricultural films and other fields, and market demand is growing year by year.
[0003] Traditional blown film screws are typically designed for general-purpose plastics such as polyethylene (PE). However, due to the characteristics of PLA, such as high heat sensitivity, low melt viscosity, and fast crystallization rate, using existing blown film screws to process it can easily lead to problems such as poor film bubble stability and low production capacity. Therefore, there is a great need for a PLA-specific blown film screw to be used in the PLA blown film process. Utility Model Content
[0004] This utility model embodiment provides a special screw for PLA blown film, which improves the stability of the film bubble and the production capacity in the PLA blown film process.
[0005] To achieve the aforementioned objectives, this application adopts the following technical solution: A PLA blown film screw, comprising The conveying unit includes a cylindrical screw and a conveying screw blade connected to the cylindrical screw. The conveying screw blade is H1 above the cylindrical screw. A barrier conveying unit connected to a conveying unit, the barrier conveying unit including a cylindrical screw and a barrier conveying mechanism connected to the cylindrical screw; A first mixing section connected to the barrier conveying section includes a conical screw and mixing blades disposed on the conical screw. The diameter of the conical screw gradually increases from left to right, and the mixing blades are evenly distributed on the conical screw. A shearing section connected to the first mixing section includes a cylindrical screw and a plurality of pins disposed on the cylindrical screw, the pins extending outward; An extrusion section connected to the shearing section, the extrusion section including a screw and multiple extrusion mechanisms connected to the screw; A second mixing section connected to the extrusion section; From left to right, they are the conveying section, the barrier conveying section, the first mixing section, the shearing section, the extrusion section, and the second mixing section.
[0006] In some alternative implementations, the distance H1 between the conveying blades and the cylindrical screw is always the same from left to right.
[0007] In some alternative implementations, 2cm
[0008] In some alternative embodiments, the barrier conveying mechanism includes at least five groups of barrier conveying components.
[0009] In some alternative embodiments, the barrier conveying component includes a barrier plate and stirring plates connected to the barrier plate. The stirring plates are distributed on the edges of the barrier plate, and are located on the opposite side walls of the barrier plate and protrude from the opposite side surfaces of the barrier plate.
[0010] In some alternative embodiments, the included angle between the stirring plate and the barrier plate is α, and 45° < α < 90°.
[0011] In some alternative embodiments, the inclination angle of the conical screw is β, and 0° < β < 30°.
[0012] In some alternative embodiments, the distance that the mixing spiral sheet protrudes from the conical screw is H2, and 2 cm < H2 < 5 cm. And as the diameter of the conical screw increases, the distance H2 that the mixing spiral sheet protrudes from the conical screw gradually decreases.
[0013] In some alternative embodiments, the length of the conical screw in the first mixing part is L1, and the length of the conical screw in the second mixing part is L2, and L2 < L1.
[0014] In some alternative embodiments, the extrusion mechanism includes a number of extrusion diamond patterns, which are evenly distributed on the outer side wall of the screw.
[0015] The special screw for PLA blown film provided by the present application has the following beneficial effects: In the technical solution adopted by the present application, the special screw for PLA blown film includes a conveying part, a barrier conveying part connected to the conveying part, a first mixing part connected to the barrier conveying part, a shearing part connected to the first mixing part, an extrusion part connected to the shearing part, and a second mixing part connected to the extrusion part. The conveying part includes a cylindrical screw and a conveying spiral sheet connected to the cylindrical screw. The distance that the conveying spiral sheet protrudes from the cylindrical screw is H1. The barrier conveying part includes a cylindrical screw and a barrier conveying mechanism connected to the cylindrical screw. The first mixing part includes a conical screw and mixing spiral sheets arranged on the conical screw. The diameter of the conical screw gradually increases from left to right. The mixing spiral sheets are evenly distributed on the conical screw. The shearing part includes a cylindrical screw and a number of pins arranged on the cylindrical screw. The pins extend outwards. The extrusion part includes a screw and a number of extrusion mechanisms connected to the screw. In sequence from left to right, there are a conveying part, a barrier conveying part, a first mixing part, a shearing part, an extrusion part and a second mixing part, which improves the stability of the film bubble and the production capacity in the PLA blown film process. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] By reading the detailed description of the non-restrictive embodiments made with reference to the following drawings, other features, objects and advantages of the present application will become more obvious: Figure 1 This is an overall structural diagram of a PLA blown film screw according to this application; Figure 2 This is a partial structural diagram of the conveying section in a PLA blown film screw according to this application; Figure 3 This is a partial structural diagram of the barrier conveying section in a PLA blown film special screw of this application; Figure 4 yes Figure 3 Enlarged view of circle A shown; Figure 5 This is a structural diagram of the connection between the barrier plate and the stirring plate in a PLA blown film screw according to this application; Figure 6 This is a partial structural diagram of the first mixing section in a PLA blown film screw according to this application; Figure 7 This is a partial structural diagram of the extrusion section in a PLA blown film screw according to this application; Figure 8 This is a partial structural diagram of the shearing section in a PLA blown film screw according to this application.
[0017] Figure label: 10. Conveying section; 11. Cylindrical screw; 12. Conveying screw blades; 20. Barrier conveying unit; 21. Barrier conveying mechanism; 22. Barrier conveying assembly; 23. Barrier plate; 24. Mixing plate; 30. First mixing section; 31. Conical screw; 32. Mixing vane; 40. Shearing section; 41. Pin; 42. Straight groove; 50. Extrusion section; 51. Screw; 52. Extrusion mechanism; 53. Extrusion diamond pattern; 60. Second mixing section. Detailed Implementation
[0018] The specific embodiments of this application are described below with reference to the accompanying drawings and examples. Through the content described in this specification, those skilled in the art can clearly and completely understand the technical solution, the technical problem solved, and the resulting technical effects of this application. It is understood that the specific embodiments described herein are only for explaining this application and not for limiting it. Furthermore, for ease of description, only the parts related to this application are shown in the accompanying drawings.
[0019] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the contents described in the specification, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size should fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.
[0020] The use of terms such as "first," "second," and "the" does not imply quantity limitation and may indicate singular or plural. The terms "comprising," "including," "having," and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, processes, methods, systems that include a series of steps or modules. The product or equipment is not limited to the listed steps or units, but may also include steps or units not listed, or other steps or units inherent to these processes, methods, products, or equipment. Terms such as “connection,” “linking,” and “coupled” used in this application are not limited to physical or mechanical connections, but may also include direct or indirect electrical connections.
[0021] It should also be noted that the longitudinal section corresponding to the embodiment of this application can be the section corresponding to the front view direction, the transverse section can be the section corresponding to the right view direction, and the horizontal section can be the section corresponding to the top view direction.
[0022] Furthermore, where there is no conflict, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.
[0023] refer to Figure 1 , Figure 1 This is an overall structural diagram of a PLA blown film screw according to this application. Figure 1 As shown, a PLA blown film screw includes a conveying section 10, a barrier conveying section 20 connected to the conveying section 10, a first mixing section 30 connected to the barrier conveying section 20, a shearing section 40 connected to the first mixing section 30, an extrusion section 50 connected to the shearing section 40, and a second mixing section 60 connected to the extrusion section 50. From left to right, the components are the conveying section 10, the barrier conveying section 20, the first mixing section 30, the shearing section 40, the extrusion section 50, and the second mixing section 60.
[0024] Continue to refer to Figure 1 Please refer to them together. Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 , Figure 2This is a partial structural diagram of the conveying section in a PLA blown film screw according to this application. Figure 3 This is a partial structural diagram of the barrier conveying section in a PLA blown film screw according to this application. Figure 4 yes Figure 3 The enlarged view of circle A shown. Figure 5 This is a structural diagram of the connection between the barrier plate and the stirring plate in a PLA blown film screw according to this application. Figure 6 This is a partial structural diagram of the first mixing section in a PLA blown film screw according to this application. Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, the conveying unit 10 includes a cylindrical screw 11 and a conveying screw 12 connected to the cylindrical screw 11. The conveying screw 12 is positioned at a distance H1, which is 2 cm above the cylindrical screw 11.
[0025] Continue to refer to Figure 1 Please refer to them together. Figure 7 and Figure 8 , Figure 7 This is a partial structural diagram of the extrusion section in a PLA blown film screw according to this application. Figure 8 This is a partial structural diagram of the shearing section in a PLA blown film screw according to this application. Figure 1 , Figure 7 and Figure 8 As shown, the shearing part 40 includes a columnar screw 11 and a plurality of pins 41 arranged on the columnar screw 11. The pins 41 extend outwards, and straight grooves 42 are formed between adjacent pins 41 in the circumferential direction. Straight grooves 42 are also formed between adjacent pins 41 in the axial direction. Specifically, when the columnar screw 11 rotates, the plurality of pins 41 and the straight grooves 42 formed between the pins 41 cut and disperse the material into multiple strands and then mix them, fully stirring the material to make the plasticized material fully mixed. The extrusion part 50 includes a screw 51 and multiple groups of extrusion mechanisms 52 connected to the screw 51. The extrusion mechanisms 52 include a plurality of extrusion diamond patterns, which are evenly distributed on the outer sidewall of the screw. Here, the setting of the extrusion part 50 can further extrude the material and simultaneously transport it after the molten material is mixed, effectively reducing the bubble rate inside the mixed material and improving the uniformity of the material mixing. The structure of the second mixing part 60 is the same as that of the first mixing part 30, but the difference is that the length of the conical screw 31 in the second mixing part 60 is L2, and L2 < L1, so as to reduce the overall length of the PLA blown film special screw 51 and reduce the space occupancy rate. Here, while mixing the material through the second mixing part 60, it is transported to the discharge end.
[0026] Here, the PLA blown film screw 51 includes a conveying section 10, a barrier conveying section 20 connected to the conveying section 10, a first mixing section 30 connected to the barrier conveying section 20, a shearing section 40 connected to the first mixing section 30, an extrusion section 50 connected to the shearing section 40, and a second mixing section 60 connected to the extrusion section 50. The conveying section 10 includes a cylindrical screw 11 and a conveying flange 12 connected to the cylindrical screw 11. The conveying flange 12 extends beyond the cylindrical screw 11. The distance is H1. The barrier conveying section 20 includes a cylindrical screw 11 and a barrier conveying mechanism 21 connected to the cylindrical screw 11. The first mixing section 30 includes a conical screw 31 and mixing blades 32 disposed on the conical screw 31. The diameter of the conical screw 31 gradually increases from left to right. The mixing blades 32 are evenly distributed on the conical screw 31. The shearing section 40 includes a cylindrical screw 11 and a plurality of pins 41 disposed on the cylindrical screw 11. The pins 41 point outward. Extending further, the extrusion section 50 includes a screw 51 and multiple extrusion mechanisms 52 connected to the screw 51. From left to right, these are the conveying section 10, the barrier conveying section 20, the first mixing section 30, the shearing section 40, the extrusion section 50, and the second mixing section. This improves the stability and production capacity of the film bubble in the PLA blown film process. It should be noted that in daily use, the barrel that works with the PLA blown film screw 51 can be heated in a zoned temperature control manner. The area on the barrel corresponding to the conveying section 10 does not need to be heated. The area on the barrel corresponding to the barrier conveying section 20 is a low-temperature section, and the temperature can be controlled between 160℃ and 180℃ to prevent the PLA particles from melting prematurely. The areas on the barrel corresponding to the first mixing section 30, the shearing section 40, the extrusion section 50, and the second mixing section are high-temperature sections, and the temperature can be controlled between 190℃ and 210℃ to prevent the PLA from degrading due to excessive temperature.
[0027] Although this application has been described and illustrated with reference to specific embodiments thereof, such description and illustration are not limiting of this application. It will be readily understood by those skilled in the art that various changes can be made and equivalent elements can be substituted within embodiments without departing from the true spirit and scope of this application as defined by the appended claims. Illustrations may not be drawn to scale. Differences may exist between the technical representation in this application and actual implementation due to variables in the manufacturing process, etc. Other embodiments of this application may exist that are not specifically described. The description and illustrations should be considered illustrative rather than restrictive. Modifications can be made to adapt particular circumstances, materials, composition, methods, or processes to the objectives, spirit, and scope of this application. All such modifications fall within the scope of the appended claims. While the methods disclosed herein have been described with reference to specific operations performed in a particular order, it should be understood that these operations can be combined, subdivided, or reordered to form equivalent methods without departing from the teachings of this application. Therefore, unless specifically indicated herein, the order and grouping of operations do not limit this application.
Claims
1. A screw specifically for PLA blown film, characterized in that, including a conveying section (10), the conveying section (10) includes a cylindrical screw (11) and a conveying spiral blade (12) connected to the cylindrical screw (11), and the height of the conveying spiral blade (12) above the cylindrical screw (11) is H1; a barrier conveying section (20) connected to the conveying section (10), the barrier conveying section (20) includes a cylindrical screw (11) and a barrier conveying mechanism (21) connected to the cylindrical screw (11); a first mixing section (30) connected to the barrier conveying section (20), the first mixing section (30) includes a conical screw (31) and mixing spiral blades (32) arranged on the conical screw (31), the diameter of the conical screw (31) gradually increases from left to right, and the mixing spiral blades (32) are evenly distributed on the conical screw (31); a shearing section (40) connected to the first mixing section (30), the shearing section (40) includes a cylindrical screw (11) and a plurality of pins (41) arranged on the cylindrical screw (11), and the pins (41) extend outwards; an extrusion section (50) connected to the shearing section (40), the extrusion section (50) includes a screw (51) and a plurality of groups of extrusion mechanisms (52) connected to the screw (51); a second mixing section (60) connected to the extrusion section (50); From left to right, they are the conveying section (10), the barrier conveying section (20), the first mixing section (30), the shearing section (40), the extrusion section (50) and the second mixing section (60) in sequence.
2. The PLA blown film screw according to claim 1, characterized in that, From left to right, the height H1 of the conveying spiral blade (12) above the cylindrical screw (11) is always the same.
3. The PLA blown film screw according to claim 2, characterized in that, 2 cm < H1 < 5 cm.
4. The PLA blown film screw according to claim 3, characterized in that, The barrier conveying mechanism (21) includes at least five groups of barrier conveying components (22).
5. The PLA blown film screw according to claim 4, characterized in that, The barrier conveying component (22) includes a barrier plate (23) and a stirring plate (24) connected to the barrier plate (23), the stirring plates (24) are distributed on the edges of the barrier plate (23), and the stirring plates (24) are located on the opposite side walls of the barrier plate (23) and protrude from the opposite side surfaces of the barrier plate (23).
6. The PLA blown film screw according to claim 5, characterized in that, The included angle between the stirring plate (24) and the barrier plate (23) is α, 45° < α < 90°.
7. The PLA blown film screw according to claim 6, characterized in that, The inclination angle of the conical screw (31) is β, 0° < β < 30°.
8. The PLA blown film screw according to claim 7, characterized in that, The height of the mixing spiral blade (32) above the conical screw (31) is H2, 2 cm < H2 < 5 cm, and as the diameter of the conical screw (31) increases, the height H2 of the mixing spiral blade (32) above the conical screw (31) gradually decreases.
9. The PLA blown film screw according to claim 8, characterized in that, The length of the conical screw (31) in the first mixing section (30) is L1, and the length of the conical screw (31) in the second mixing section (60) is L2, L2 < L1.
10. The PLA blown film screw according to claim 9, characterized in that, The extrusion mechanism (52) includes a number of extrusion diamond patterns (53), and the extrusion diamond patterns (53) are evenly distributed on the outer side wall of the screw (51).