Physical foaming screw and plastic molding apparatus
By designing equal-volume feeding, compression, and homogenization sections with varying screw channel volumes, as well as double-sided wavy screw channels and alternating height spiral rib structures, the problems of localized high pressure and high shear stress damage in the melt in existing technologies have been solved. This has enabled efficient mixing and the formation of a homogeneous system, thereby improving the production efficiency of plastic molding equipment and the quality of finished products.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- GUANGDONG YIZUMI PRECISION MACHINERY CO LTD
- Filing Date
- 2025-07-14
- Publication Date
- 2026-07-10
AI Technical Summary
Existing physical foaming screws suffer from significant volume differences between the compression and homogenization sections, leading to localized high pressure and high shear stress in the melt that damage the material. The depth and shape of the screw channel in the homogenization section cannot balance the requirements for low shear and efficient mixing. The lack of dynamic shear force changes in the mixing section makes it difficult for the foaming agent and the melt to form a homogeneous system.
A physically foaming screw is designed. By setting the screw channel volume ratio and structure of the feeding section, compression section, homogenization section and mixing section, and adopting a double-sided wavy screw channel and an alternating height helical ridge shearing structure, an equal volume design, shallow and gradually changing channel depth and dynamic shear force variation are achieved to form a fine microstructure.
To avoid damage from localized high pressure and high shear stress in the melt, balance low shear with efficient mixing, improve the mixing and homogenization efficiency of the foaming agent and the melt, shorten the plasticizing time, and improve product quality and production efficiency.
Smart Images
Figure CN224476459U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of plastic molding technology, and in particular to a physically foamed screw and plastic molding equipment. Background Technology
[0002] The screw is an important component of plastic molding equipment such as injection molding machines or extruders. Among them, the physical foaming screw refers to a screw structure used for physical foaming and mixing of supercritical fluids and low-shear dispersion reinforcing materials (such as hollow microspheres and glass fibers). It usually includes a feeding section, a compression section, a homogenization section and a mixing section. The feeding section transports raw materials, the compression section realizes melting and preliminary mixing, the homogenization section ensures uniform and stable melt, and the mixing section disperses and mixes foaming agents such as supercritical fluids and melts, thereby efficiently completing the physical foaming molding process of plastics. In the existing technology, the physical foaming screw has the following problems: (1) The volume difference between the compression section and the homogenization section is large, which causes local high pressure and high shear stress in the melt, damaging glass fibers or hollow microspheres; (2) The depth and shape of the screw channel in the homogenization section cannot balance the requirements of low shear and efficient mixing; (3) The dispersing structure of the mixing section lacks dynamic shear force changes, and it is difficult for the foaming agent and melt to form a homogeneous system.
[0003] It should be noted that the above content is only used to help understand the technical solution of this utility model, and does not represent an admission that the above content is prior art. Utility Model Content
[0004] The main purpose of this invention is to propose a physical foaming screw and a plastic molding equipment, which aims to achieve (1) avoid local high pressure and high shear stress in the melt; (2) balance the requirements of low shear and efficient mixing; and (3) realize dynamic shear force change so that the foaming agent and the melt form a homogeneous system.
[0005] To achieve the above objectives, this utility model proposes a physically foamed screw;
[0006] Specifically, the physical foaming screw includes a feeding section, a compression section, a homogenization section, and a mixing section arranged sequentially along the plastic's forward direction; the volume of a single screw channel in the feeding section is defined as V1, the volume of a single screw channel in the compression section is V2, and the volume of a single screw channel in the homogenization section is V3, where V3 = V2 = 1.2~1.5 V1; the screw channel in the homogenization section has a double-sided wavy structure, and the local depth of the screw channel gradually changes from shallow to thin.
[0007] The mixing section includes a dispersing structure and a mixing structure arranged sequentially along the plastic's forward direction. The dispersing structure includes a first spiral ridge and a second spiral ridge spaced apart along the circumferential direction of the mixing section, wherein the height of the second spiral ridge is less than the height of the first spiral ridge.
[0008] In one embodiment, the unit length is defined as D, the length of the feeding section is 8D, the length of the compression section is 4D, the length of the homogenization section is 8D, the length of the dispersing structure is 3D, and the length of the mixing structure is D.
[0009] In one embodiment, the pitch of the feeding section is defined as P1, and the pitch of the compression section is defined as P2, where P2 ≥ P1.
[0010] In one embodiment, the pitch of the homogenization section is P3, where P3 > 1.2~2 P2.
[0011] In one embodiment, the screw groove depth of the feeding section is defined as H1, and the screw groove depth of the compression section is defined as H2, where H2 < H1.
[0012] In one embodiment, the groove depth of the homogenization section is defined as H3, where H3 < H2.
[0013] In one embodiment, the groove depth of the homogenization section varies from 0.5 to 1.2 mm.
[0014] In one embodiment, the height difference between the first helical ridge and the second helical ridge is less than 5 mm; or, the height difference between the first helical ridge and the second helical ridge is less than 4 mm and greater than 0.5 mm.
[0015] In one embodiment, the mixing structure includes at least one mixing group, and the at least one mixing group is spaced apart along the axial direction of the mixing section; each mixing group includes at least two mixing protrusions, and the mixing protrusions in the same mixing group are spaced apart along a preset spiral direction.
[0016] To achieve the above objectives, this utility model proposes a plastic molding equipment, which includes a physically foaming screw as described in any of the above claims.
[0017] The first aspect of the technical solution of this utility model specifies that the volume of a single screw channel in the feeding section, compression section, and homogenization section is V3=V2=1.2~1.5. V1. To maintain equal volumes in the compression and homogenization sections, preventing damage to glass fibers or hollow microspheres due to localized high pressure and shear stress in the melt; secondly, the spiral grooves in the homogenization section are designed with a double-sided wavy structure, and the depth of the grooves gradually changes in shallowness. This gradual change in depth disperses shear stress, balancing the requirements of low shear and efficient mixing; thirdly, the dispersing structure in the mixing section includes a first spiral ridge and a second spiral ridge spaced apart along the circumferential direction of the mixing section, with the height of the second spiral ridge being less than that of the first spiral ridge. This alternating shearing of the foaming agent and melt by the spiral ridges with height differences achieves dynamic shear force changes, which is beneficial for forming a fine microstructure. The fine microstructure after dispersing allows for faster and more uniform mixing and blending on the homogenized structure, forming a more stable homogeneous system, thereby improving the mixing and homogenization efficiency of the foaming agent and melt and shortening the plasticizing time. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 A schematic diagram of a physical foaming screw according to an embodiment of the present invention;
[0020] Figure 2 for Figure 1 Sectional view of the cross section at point AA;
[0021] Figure 3 A schematic diagram of the mixing section in one embodiment of the physically foaming screw provided by this utility model.
[0022] Explanation of reference numerals in the attached figures:
[0023] 10. Feeding section; 20. Compression section; 30. Homogenization section; 40. Mixing section; 50. Dispersing structure; 51. First spiral ridge; 52. Second spiral ridge; 60. Mixing structure; 61. Mixing group; 62. Mixing protrusion;
[0024] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0025] The technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, what is described is only a part of the embodiments of this utility model, and not all of the embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.
[0026] It should be noted that if the embodiments of this utility model involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.
[0027] Furthermore, it should be noted that the descriptions involving "first," "second," etc., in this utility model are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.
[0028] The screw is an important component of plastic molding equipment such as injection molding machines or extruders. Among them, the physical foaming screw refers to a screw structure used for physical foaming and mixing of supercritical fluids and low-shear dispersion reinforcing materials (such as hollow microspheres and glass fibers). It usually includes a feeding section, a compression section, a homogenization section and a mixing section. The feeding section transports raw materials, the compression section realizes melting and preliminary mixing, the homogenization section ensures uniform and stable melt, and the mixing section disperses and mixes foaming agents such as supercritical fluids and melts, thereby efficiently completing the physical foaming molding process of plastics. In the existing technology, the physical foaming screw has the following problems: (1) The volume difference between the compression section and the homogenization section is large, which causes local high pressure and high shear stress in the melt, damaging glass fibers or hollow microspheres; (2) The depth and shape of the screw channel in the homogenization section cannot balance the requirements of low shear and efficient mixing; (3) The dispersing structure of the mixing section lacks dynamic shear force changes, and it is difficult for the foaming agent and melt to form a homogeneous system.
[0029] To solve the above-mentioned technical problems, this utility model proposes a physically foamed screw.
[0030] Please see Figures 1 to 3In one embodiment of this utility model, the physical foaming screw includes a feeding section 10, a compression section 20, a homogenization section 30, and a mixing section 40 arranged sequentially along the plastic advancing direction; the volume of a single screw channel in the feeding section 10 is defined as V1, the volume of a single screw channel in the compression section 20 is defined as V2, and the volume of a single screw channel in the homogenization section 30 is defined as V3, wherein V3 = V2 = 1.2~1.5 V1; the screw channel of the homogenization section 30 has a double-sided wavy structure, and the local groove depth within the screw channel gradually changes from shallow to thin.
[0031] The mixing section 40 includes a dispersing structure 50 and a mixing structure 60 arranged sequentially along the plastic advancing direction. The dispersing structure 50 includes a first spiral ridge 51 and a second spiral ridge 52 arranged at intervals along the circumferential direction of the mixing section 40. The height of the second spiral ridge 52 is less than the height of the first spiral ridge 51.
[0032] In the first aspect of the technical solution of this embodiment, the individual screw channel volumes of the feeding section 10, the compression section 20, and the homogenization section 30 are specified as V3=V2=1.2~1.5. V1, to maintain equal volumes in the compression section 20 and homogenization section 30, avoiding damage to glass fibers or hollow microspheres due to local high pressure and high shear stress in the melt; secondly, the spiral groove of the homogenization section 30 is set as a double-sided wavy structure, and the local groove depth within the spiral groove is shallow and gradually changed. The shallow and gradually changed depth can disperse shear stress to balance the requirements of low shear and efficient mixing; thirdly, the dispersing structure 50 of the mixing section 40 includes a first spiral ridge 51 and a second spiral ridge 52 spaced apart along the circumferential direction of the mixing section 40, wherein the height of the second spiral ridge 52 is less than the height of the first spiral ridge 51. In this way, the alternating shearing of the foaming agent and the melt by the spiral ridges with height difference can achieve dynamic shear force changes, which is conducive to forming a fine microstructure; the fine microstructure after dispersing can be further mixed and blended more quickly and uniformly on the homogenization structure 60 to form a more stable homogeneous system, thereby improving the mixing and homogenization efficiency of the foaming agent and the melt and shortening the plasticizing time.
[0033] As a preferred embodiment of the above, the unit length is defined as D. The length of the feeding section 10 is 8D, the length of the compression section 20 is 4D, the length of the homogenization section 30 is 8D, the length of the dispersing structure 50 is 3D, and the length of the mixing structure 60 is D. This configuration clearly defines the specific proportional relationship of each section length, allowing each section of the screw to fully perform its function during the plastic molding process. The relatively long feeding section 10 ensures sufficient material conveying time; the length design of the compression section 20 and the homogenization section 30 helps to achieve efficient melting and homogenization; the length design of the dispersing structure 50 and the mixing hole structure 60 ensures that the foaming agent and the melt can be fully dispersed and mixed. This length allocation optimizes the overall performance of the screw, improving production efficiency and product quality.
[0034] As a preferred embodiment of the above, the pitch of the feeding section 10 is defined as P1, and the pitch of the compression section 20 is defined as P2, where P2 ≥ P1. This configuration, by setting the pitch of the compression section 20 to P2 ≥ P1, allows the plastic to be more effectively compressed and sheared after entering the compression section 20, thereby accelerating the melting process, improving the mixing uniformity of the melt, and contributing to enhancing the processing performance of the screw.
[0035] Furthermore, the pitch of the homogenization section 30 is P3, where P3 > 1.2~2 P2. This setting, with a pitch P3 > 1.2~2 P2, further enhances the mixing effect of the melt in the homogenization section 30. A larger pitch allows the melt to remain in the screw channel for a longer time, thus achieving more thorough mixing and homogenization, further improving the uniformity of the product quality, and reducing melt temperature fluctuations.
[0036] As a preferred embodiment of the above, the screw groove depth of the feeding section 10 is defined as H1, and the screw groove depth of the compression section 20 is defined as H2, where H2 < H1. This design, with the screw groove depth of the compression section 20 H2 < H1, allows the plastic to undergo a greater compression ratio in the compression section 20, thereby accelerating the melting process and reducing material residue in the compression section 20, thus improving the screw's production efficiency and processing stability.
[0037] Furthermore, the groove depth of the homogenization section 30 is defined as H3, where H3 < H2. This setting, with a groove depth of H3 < H2, further optimizes the flow characteristics of the melt in the homogenization section 30. A shallower groove depth increases the shear force of the melt, promoting mixing and homogenization, while avoiding material degradation caused by excessive shearing, thus improving the quality and performance of the product.
[0038] As a preferred embodiment of the above, the groove depth of the homogenization section 30 varies from 0.5 to 1.2 mm. This setting, limiting the groove depth of the homogenization section 30 to a range of 0.5 to 1.2 mm, allows for precise control of the melt flow and mixing effect within the homogenization section 30. This depth variation range ensures thorough mixing of the melt while avoiding excessive melt flow resistance due to overly shallow grooves, thereby achieving an efficient homogenization process and improving the uniformity and stability of the product quality.
[0039] As a preferred embodiment of the above, the height difference between the first spiral ridge 51 and the second spiral ridge 52 is less than 5 mm; with this setting, this height difference range enables the spiral ridge assembly to further improve the dispersing ability of the spiral ridge assembly, and further improve the mixing and homogenization efficiency of the foaming agent and the melt.
[0040] Furthermore, the height difference between the first helical ridge 51 and the second helical ridge 52 is less than 4 mm and greater than 0.5 mm. With this setting, the helical ridge group within this height difference range can have better shearing force, further improving the disintegration ability of the helical ridge group.
[0041] As a preferred embodiment of the above embodiments, the mixing structure 60 includes at least one mixing group 61, which is spaced apart along the axial direction of the mixing section 40; each mixing group 61 includes at least two mixing protrusions 62, which are spaced apart along a predetermined spiral direction. With this configuration, the mixing structure 60 improves the fine microstructure of the melt and foaming agent after dispersion, as well as the mixing efficiency with the polymer melt, further shortening the plasticizing time and the manufacturing cycle of plastic products.
[0042] This utility model also discloses a plastic molding apparatus, including a physically foamed screw according to any of the above embodiments. The specific structure of the physically foamed screw can be referred to the above embodiments. Since this plastic molding apparatus adopts all the technical solutions of all the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be elaborated further here.
[0043] It should be noted that the physical foaming screw and other contents of the plastic molding equipment disclosed in this utility model are existing technologies and will not be described in detail here.
[0044] The above are merely optional embodiments of this utility model and do not limit the patent scope of this utility model. Any application of this utility model directly or indirectly in other related technical fields is included within the patent protection scope of this utility model.
Claims
1. A physically foamed screw, characterized in that, The physical foaming screw includes a feeding section, a compression section, a homogenization section, and a mixing section arranged sequentially along the plastic's forward direction; the volume of a single screw channel in the feeding section is defined as V1, the volume of a single screw channel in the compression section is defined as V2, and the volume of a single screw channel in the homogenization section is defined as V3, where V3 = V2 = 1.2~1.5 V1; the screw channel in the homogenization section has a double-sided wavy structure, and the depth of the local grooves gradually changes from shallow to thin. The mixing section includes a dispersing structure and a mixing structure arranged sequentially along the plastic's forward direction. The dispersing structure includes a first spiral ridge and a second spiral ridge spaced apart along the circumferential direction of the mixing section, wherein the height of the second spiral ridge is less than the height of the first spiral ridge.
2. The physically foamed screw as described in claim 1, characterized in that: The unit length is defined as D, the length of the feeding section is 8D, the length of the compression section is 4D, the length of the homogenization section is 8D, the length of the dispersing structure is 3D, and the length of the mixing structure is D.
3. The physically foamed screw as described in claim 1, characterized in that: The pitch of the feeding section is defined as P1, and the pitch of the compression section is defined as P2, where P2 ≥ P1.
4. The physically foamed screw as described in claim 3, characterized in that: The pitch of the homogenization section is P3, where P3 > 1.2~2 P2.
5. The physically foamed screw as described in claim 1, characterized in that: The screw groove depth of the feeding section is defined as H1, and the screw groove depth of the compression section is defined as H2, where H2 < H1.
6. The physically foamed screw as described in claim 5, characterized in that: The groove depth of the homogenization section is defined as H3, where H3 < H2.
7. The physically foamed screw as described in claim 6, characterized in that: The depth of the groove in the homogenization section varies from 0.5 to 1.2 mm.
8. The physically foamed screw as described in claim 1, characterized in that: The height difference between the first spiral edge and the second spiral edge is less than 5 mm; or, the height difference between the first spiral edge and the second spiral edge is less than 4 mm and greater than 0.5 mm.
9. The physically foamed screw as described in claim 1, characterized in that: The mixing structure includes at least one mixing group, and the at least one mixing group is arranged at intervals along the axial direction of the mixing section; each mixing group includes at least two mixing protrusions, and the mixing protrusions in the same mixing group are arranged at intervals along a preset spiral direction.
10. A plastic molding equipment, characterized in that: The plastic molding equipment includes a physically foaming screw as described in any one of claims 1 to 9.