Plasticizing screw

Abstract

A plasticizing screw includes a feed section, a melt section including a first melt sub-section and a second melt sub-section, where: the first melt sub-section and the second melt sub-section are configured to have different melt operations, the first melt sub-section being upstream of the second melt sub-section, and the mixing section being downstream of the second melt sub-section. And the length of the second melt sub-section is between 37% and 67% of the length of the melt section.

Description

Technical Field

[0001] This technology relates to plasticizing screws, such as, but not limited to, plasticizing screws for extruders used to convert solid polymers into polymer melts. Background Technology

[0002] Plasticizing screws for extruders typically include a slender shaft rotatably housed within a barrel. Plasticizing screws come in a variety of different designs, tailored to perform specific functions, such as conveying materials to be melted, compressed, molten, pressurized, and mixed within the barrel.

[0003] U.S. Patent No. 7,296,920 to Husky Injection Molding Systems Ltd. discloses a plasticizing screw configured to increase flow rate without changing screw size.

[0004] U.S. Patent No. 6,227,692 to Husky Injection Systems, Inc. discloses a plasticizing screw configured to achieve homogeneous mixing and melting without increasing total shear force.

[0005] U.S. Patent No. 4,770,539 to Husky Injection Systems, Inc. discloses a plasticizing screw configured to provide homogeneous molten plastic material. Summary of the Invention

[0006] One object of the present invention is to improve upon at least some of the deficiencies present in the prior art. More specifically, the prior art does not appear to provide a plasticizing screw that includes all the functions of homogeneous mixing and high output.

[0007] Therefore, one objective of this technology is to provide a plasticizing screw that has a high melt material output and homogeneous mixing within the melt.

[0008] Another objective of this technology is to provide a plasticizing screw that has a high melt output, homogeneous mixing within the melt, and avoids degradation byproducts of the material during melting.

[0009] In summary, embodiments of this technology relate to a plasticizing screw for a molding machine, the plasticizing screw including a feeding section, a melting section, and a mixing section, wherein the melting section includes a first melting sub-section and a second melting sub-section, wherein the first melting sub-section and the second melting sub-section are configured to have different melting operations, the first melting sub-section is upstream of the second melting sub-section, and the length of the second melting sub-section is between 60% and 67% of the length of the melting section.

[0010] In some non-limiting embodiments, the length of the second melt sub-section is between 30% and 34% of the effective length of the plasticizing screw.

[0011] In some non-limiting embodiments, the first molten sub-section is configured to operate using a layered melting effect.

[0012] In some non-limiting embodiments, the first molten sub-section includes a screw root whose diameter increases toward the screw's outlet end.

[0013] In some non-limiting embodiments, the diameter at the screw root increases by 12% to 17% toward the outlet end.

[0014] In some non-limiting embodiments, the diameter at the screw root increases by more than 16% toward the outlet end.

[0015] In some non-limiting embodiments, the second molten sub-section is configured to operate using a dispersive melting effect.

[0016] In some non-limiting embodiments, the second molten sub-section includes a wave zone having a plurality of convex ridges alternately offset relative to the screw root.

[0017] In some non-limiting embodiments, the length of the mixing section exceeds 13% of the effective length of the plasticizing screw.

[0018] In some non-limiting embodiments, the length of the mixing section is between 14% and 34% of the effective length of the screw.

[0019] In some non-limiting embodiments, the mixing segment includes a first mixing sub-segment and a second mixing sub-segment, which are configured to have different mixing operations.

[0020] In some non-limiting embodiments, the second hybrid sub-segment is configured to operate via distributed hybridization.

[0021] In some non-limiting embodiments, the second mixing sub-section includes a pineapple mixer.

[0022] In some non-limiting embodiments, the length of the pineapple mixer exceeds 5% of the effective length of the screw.

[0023] In some non-limiting embodiments, the length of the pineapple mixer is 6-23% of the effective length of the screw.

[0024] In some non-limiting embodiments, the length of the pineapple mixer exceeds 36% of the length of the mixing section.

[0025] In some non-limiting embodiments, the length of the pineapple mixer is 37-67% of the length of the mixing section.

[0026] According to another aspect, a plasticizing screw for a molding machine is provided, the plasticizing screw comprising: a feeding section, a melting section and a mixing section, the mixing section comprising a first mixing sub-section and a second mixing sub-section, the second mixing sub-section being configured to operate by distributed mixing and having a length of 37%-67% of the length of the mixing section.

[0027] In some non-limiting embodiments, the length of the mixing section exceeds 13% of the effective length of the plasticizing screw.

[0028] In some non-limiting embodiments, the length of the mixing section is 14-34% of the effective length of the plasticizing screw.

[0029] In some non-limiting embodiments, the second mixing sub-section includes a pineapple mixer.

[0030] In some non-limiting embodiments, the melt sub-segment includes a first melt sub-segment and a second melt sub-segment, which are configured to have different melting operations, and the length of the second melt sub-segment is between 60% and 67% of the length of the melt sub-segment.

[0031] In some non-limiting embodiments, the length of the second melt sub-section is between 30% and 34% of the effective length of the plasticizing screw.

[0032] In some non-limiting embodiments, the second molten sub-section is configured to operate using a dispersive melting effect.

[0033] In some non-limiting embodiments, the second molten sub-section includes a wave zone having a plurality of convex ridges alternately offset relative to the screw root.

[0034] According to another aspect, a plasticizing screw for a molding machine is provided, the plasticizing screw comprising: a feeding section, a melting section and a mixing section, the mixing section comprising a first mixing sub-section and a second mixing sub-section, the first mixing sub-section being configured to operate by dispersion mixing and having a length of 8-10% of the effective length of the plasticizing screw.

[0035] In some non-limiting embodiments, the length of the mixing section exceeds 13% of the effective length of the plasticizing screw.

[0036] In some non-limiting embodiments, the length of the mixing section is 14-34% of the effective length of the plasticizing screw.

[0037] In some non-limiting embodiments, the first mixing sub-section includes a spiral mixer.

[0038] In some non-limiting embodiments, the melt sub-segment includes a first melt sub-segment and a second melt sub-segment, which are configured to have different melting operations, and the length of the second melt sub-segment is between 37% and 67% of the length of the melt sub-segment.

[0039] In some non-limiting embodiments, the length of the second melt sub-section is between 6% and 23% of the effective length of the plasticizing screw.

[0040] In some non-limiting embodiments, the second molten sub-section is configured to operate using a dispersive melting effect.

[0041] In some non-limiting embodiments, the second molten sub-section includes a wave zone having a plurality of convex ridges alternately offset relative to the screw root.

[0042] In the context of this specification, the words “first,” “second,” “third,” etc., are used as adjectives solely to distinguish the nouns they modify, and not to describe any specific relationship between those nouns. Furthermore, as discussed in other contexts herein, references to “first” and “second” elements do not preclude the existence of the same actual, real-world element.

[0043] These and other aspects and features of the non-limiting embodiments of the present technology will become apparent to those skilled in the art after reading the following description of specific non-limiting embodiments in conjunction with the accompanying drawings.

[0044] The embodiments of this technology each have at least one of the above-described objectives and / or aspects, but not necessarily all of them. It should be understood that some aspects of this technology arising from attempts to achieve the above objectives may not satisfy those objectives and / or may satisfy other objectives not specifically described herein.

[0045] Additional and / or alternative features, aspects, and advantages of embodiments of the present technology will become apparent from the following description, the accompanying drawings, and the appended claims. Attached Figure Description

[0046] Embodiments of the present technology (including its alternatives and / or variations) can be better understood by referring to the detailed description of non-limiting embodiments and the following drawings, wherein:

[0047] Figure 1 This is a side cross-sectional view of a plasticizing screw housed in a barrel according to an embodiment of the present invention.

[0048] Figure 2 According to the embodiments of this technology Figure 1 A side view of the melting section of the plasticizing screw, which includes two melting sub-sections.

[0049] Figure 3 According to the embodiments of this technology Figure 2 A perspective view of one of the two molten sub-sections.

[0050] Figure 4 According to the embodiments of this technology Figure 2 BB line passes through Figure 3 Cross-section of the molten sub-section.

[0051] Figure 5 According to the embodiments of this technology Figure 1 A side view of the mixing section of the plasticizing screw, which includes two mixing sub-sections.

[0052] Figures 6 and 7 are side views of prior art plasticizing screws. Detailed Implementation

[0053] Reference will now be made in detail to various non-limiting embodiments of the plasticizing screw. It should be understood that, in view of the non-limiting embodiments disclosed herein, other non-limiting embodiments, modifications, and equivalents will be apparent to those skilled in the art, and these variations should be considered within the scope of the appended claims.

[0054] Furthermore, those skilled in the art will recognize that certain structural and operational details of the non-limiting embodiments discussed below may be modified or omitted entirely (i.e., are not essential). In other instances, well-known methods, steps, and components are not described in detail.

[0055] refer to Figure 1 A screw 10 for a molding machine (not shown) is provided, the screw 10 including a feed section 12, a melting section 14, and a mixing section 16. The screw 10 has a screw root 18, which is continuous and extends along the effective length 24 of the screw 10 between a feed end 20 and an outlet end 22. The screw root 18 may have any desired diameter 26, which may depend at least on the specific application of the screw 10.

[0056] The screw 10 is configured to be rotatably housed in a barrel 28 having a barrel wall 29. The barrel 28 can be heated along at least a portion of the effective length 24 of the screw 10. The barrel 28 has an inlet port 30 for receiving material to be molten (e.g., polymer particles) and an outlet port 32 through which the molten material can be discharged into a mold or the like. The polymer can include any polymer, such as polyethylene terephthalate (PET) or PET blends. The outlet port 32 of the barrel 28 can be in fluid communication with an injection molding machine (e.g., an injection molding machine for forming containers).

[0057] In use, the screw 10 is disposed in the barrel 28 such that the feed end 20 is disposed near the inlet port 30 of the barrel 28, and the outlet end 22 is disposed near the outlet port 32 of the barrel 28. The screw root 18 can be rotatably driven at the feed end 20 of the screw 10 at the desired rotational speed by a conventional device (not shown).

[0058] The feed section 12 includes a single feed thread 34 configured to convey material to be melted from the feed end 20 toward the outlet end 22. Compaction of the solid material and some melting are expected in the feed section 12. A single feed thread 26 is helically arranged around the screw root 18 and, in the illustrated embodiment, is helical, defining a helical channel 36 within the barrel 28. The single feed thread 34 has a uniform depth 38 and a uniform pitch 40 within the feed section 12. The channel 36 defined by the barrel 28 and the screw 10 in the feed section 12 also has a uniform depth.

[0059] In the feed section 12, the ratio of the depth 38 of the thread 34 to the diameter 26 of the screw root 18 is between approximately 19% and approximately 24%.

[0060] Now for reference Figure 1 and Figure 2 The melting section 14 includes a first melting sub-section 42 and a second melting sub-section 44. The first melting sub-section 42 is downstream of the feed section 12 and upstream of the second melting sub-section 44. The first melting sub-section 42 and the second melting sub-section 44 are configured to have different melting operations.

[0061] The first melting sub-section 42 is configured to operate using a stratified melting effect. The first melting sub-section 42 may also be referred to as a compression section. The first melting sub-section 42 is configured to compress solid material and press it against the wall of the barrel 28 as the screw 10 rotates.

[0062] The feed thread 34 extends from the feed section 12 to the first melting sub-section 42, with the same thread depth 38 and pitch 40. Along the length 46 of the first melting sub-section 42, the diameter 26 of the screw root 18 increases towards the second melting sub-section 44. In other words, the screw root 18 is tapered, causing the channel 36 defined between the barrel 28 and the screw root 18 in the first melting sub-section 42 to become shallower towards the second melting sub-section 44. The depth 48 of the channel 36 at its inlet is greater than that at its outlet. In some embodiments, the taper of the screw root 18 is linear.

[0063] The taper of the screw root 18 increases the pressure within the channel 36, which can increase the melting rate of the material in the channel 36. In some embodiments, the diameter 26 of the screw root 18 is increased by about 12% to about 17%. In some embodiments, the diameter 32 of the screw root 18 is increased by more than about 16%. Compression can also be represented by a change in the depth of the channel 36, which decreases.

[0064] The length 46 of the first molten sub-section 28 is approximately 19% of the effective length 24 of the screw 10. The length 46 of the first molten sub-section 28 is approximately 37% to approximately 38% of the length 54 of the molten section 14.

[0065] The second molten sub-section 44 is downstream of the first molten sub-section 42. The second molten sub-section 44 is configured to operate using a dispersive melting effect. The second molten sub-section 44 can also be referred to as a wave zone. The feed thread 34 extends from the first molten sub-section 42 to the second molten sub-section 44 with the same pitch 40. In the second molten sub-section 44, a plurality of convex ridges 50 are provided, alternately offset relative to the screw root 18. For example... Figure 3 and Figure 4 As most clearly shown, in some embodiments, two offset ridges 50 are provided between each thread pitch 40. In other words, in the second melt sub-section 44, the depth 48 of the channel 36 defined within the barrel 28 varies due to the offset of the ridges 50.

[0066] The length 52 of the second molten sub-section 44 is between approximately 30% and approximately 34% of the effective length 24 of the screw 10.

[0067] The length 52 of the second molten sub-segment 44 is between about 62% and about 64% of the length 54 of the molten segment 14. In some embodiments, the length 52 is between about 60% and about 67% of the length 54 of the molten segment 14.

[0068] In some embodiments, the construction of the second melting sub-section 44 allows material to move between the ridges 50, thereby allowing any compacted solid material bed in the channel 36 to be broken up, so that more material can be melted. The melting of the material continues via heat conduction from the hot melt, which is desirable from the perspective of reducing the amount of shear required for melting.

[0069] Now go to Figure 5 The most clearly shown is the mixing section 16. The mixing section 16 includes a first mixing sub-section 56 and a second mixing sub-section 58, which are configured to have different mixing operations.

[0070] The first mixing sub-section 56 is upstream of the second mixing sub-section 58 and downstream of the second melting sub-section 44. The first mixing sub-section 56 is configured to operate by dispersion mixing. In some embodiments, the first mixing sub-section 56 includes a helical mixer 60 having a plurality of helical ribs 62 defining a helical channel 64 therebetween. The helical ribs 62 are circular. The helical mixer 60 is configured to trap solid particles within the helical channel 64 while allowing smaller particles to pass through the gap 66 between the barrel wall 29 and the outermost dimension of the ribs 62. Figure 1 Any material trapped by the helical mixer 60 eventually melts through heat conduction. In other embodiments, instead of the helical mixer 60, any other component capable of trapping unmelted material and serving as a pressure barrier for the upstream portion of the screw, such as a barrier thread or bubble ring, can be used.

[0071] The second mixing sub-section 58 is configured to operate via distributed mixing. In some embodiments, the second mixing sub-section 58 includes a pineapple mixer 68. In other embodiments not shown, the second mixing sub-section 58 may be other forms of distributed mixers, such as Dulmage™ or Saxton™ mixers. The pineapple mixer 68 includes a plurality of protrusions 70 extending outward from the screw root 18. The protrusions 70 have a cubic configuration. In other embodiments, the protrusions 70 may be configured in any other shape, such as a pyramid.

[0072] The length 72 of the mixing section 16 is between about 14% and about 34% of the effective length 24 of the screw 10, or between about 17% and about 19%. In an embodiment where the second mixing sub-section 58 is a pineapple mixer, the length 72 of the mixing section 16 exceeds the effective length 24 of the screw 10 by about 13%.

[0073] The length of the first hybrid sub-section 56 is about 8% to about 10% or 8% to about 9% of the effective length 24 of the screw 10.

[0074] The length 74 of the second mixing sub-section 58 is between about 6% and about 23% of the effective length 24 of the screw 10, or about 8%. The length 74 of the second mixing sub-section 58 is between about 37% and about 67% of the length 72 of the mixing section 16, or about 42% and about 47%. In an embodiment where the second mixing sub-section 58 is a pineapple mixer, the length 74 of the second mixing sub-section 58 exceeds about 5% of the effective length 24 of the screw 10, or exceeds about 36% of the length 72 of the mixing section 16.

[0075] According to embodiments of the screw 10 of this technology, high melt yield and good mixing can be achieved while avoiding polymer degradation byproducts, such as acetaldehyde. Unlike some prior art screws (such as those depicted in Figures 6 and 7) that can only achieve good mixing or good yield, embodiments of this technology can achieve both functions.

[0076] Unbound by any theory, it is believed that in some embodiments of this technology, 20-40% melting of the material to be melted is achieved through the end of the first melting sub-segment 42.

[0077] In some embodiments, a first melting sub-section is configured to initiate melting, producing a mixture of molten resin and solid material; a second melting sub-section is configured to complete melting via a solid dispersion mechanism; a first mixing sub-section is configured to disperse unmixed additive agglomerates and prevent solid material from passing through; and a second mixing sub-section is configured to fully blend the melt and additives via distributed mixing.

[0078] Modifications and improvements to the above embodiments of this technology will be apparent to those skilled in the art. The above description is intended to be exemplary and not limiting. Therefore, the scope of this technology is defined only by the scope of the appended claims.

[0079] The description of embodiments of this technology provides only examples of the technology, and these examples do not limit the scope of the technology. It should be clearly understood that the scope of the technology is limited only by the claims. The above concepts can be applied to specific conditions and / or functions, and can be further extended to various other applications within the scope of this technology. Having thus described embodiments of the technology, it will be apparent that modifications and enhancements are possible without departing from the described concepts.

Claims

1. A plasticizing screw for a molding machine, the plasticizing screw comprising a feeding section, a melting section, and a mixing section, wherein: The melting section includes a first melting sub-section and a second melting sub-section, wherein: The first melting sub-section and the second melting sub-section are configured to have different melting operations. The first molten sub-section is upstream of the second molten sub-section, and The length of the second molten sub-segment is between 60% and 67% of the length of the molten segment.

2. The plasticizing screw according to claim 1, wherein the length of the second melt sub-section is between 30% and 34% of the effective length of the plasticizing screw.

3. The plasticizing screw of claim 1, wherein the first melt sub-section is configured to operate using a layered melt effect.

4. The plasticizing screw according to claim 3, wherein the first melt sub-section includes a screw root, the diameter of which increases toward the outlet end of the screw.

5. The plasticizing screw according to claim 3, wherein the diameter of the screw root increases by 12% to 17% toward the outlet end.

6. The plasticizing screw according to claim 3, wherein the diameter of the screw root increases by more than 16% toward the outlet end.

7. The plasticizing screw of claim 1, wherein the second melt sub-section is configured to operate using a dispersive melt effect.

8. The plasticizing screw according to claim 7, wherein the second melt sub-section includes a wave zone having a plurality of convex ridges alternately offset relative to the root of the screw.

9. The plasticizing screw according to claim 1, wherein the length of the mixing section exceeds 13% of the effective length of the plasticizing screw.

10. The plasticizing screw according to claim 9, wherein the length of the mixing section is between 14% and 34% of the effective length of the screw.

11. The plasticizing screw of claim 1, wherein the mixing section comprises a first mixing sub-section and a second mixing sub-section configured to have different mixing operations.

12. The plasticizing screw of claim 11, wherein the second mixing sub-section is configured to operate by distributed mixing.

13. The plasticizing screw of claim 12, wherein the second mixing sub-section comprises a pineapple mixer.

14. The plasticizing screw according to claim 12, wherein the length of the pineapple mixer exceeds 5% of the effective length of the screw.

15. The plasticizing screw according to claim 14, wherein the length of the pineapple mixer is 6-23% of the effective length of the screw.

16. The plasticizing screw of claim 12, wherein the length of the pineapple mixer exceeds 36% of the length of the mixing section.

17. The plasticizing screw according to claim 16, wherein the length of the pineapple mixer is 37-67% of the length of the mixing section.

18. A plasticizing screw for a molding machine, the plasticizing screw comprising: Feeding section, Melting zone, and The hybrid segment includes a first hybrid sub-segment and a second hybrid sub-segment, the second hybrid sub-segment being configured to operate via distributed hybridization and having a length of 37%-67% of the length of the hybrid segment.

19. The plasticizing screw according to claim 18, wherein the length of the mixing section exceeds 13% of the effective length of the plasticizing screw.

20. The plasticizing screw according to claim 19, wherein the length of the mixing section is 14-34% of the effective length of the plasticizing screw.

21. The plasticizing screw of claim 18, wherein the second mixing sub-section comprises a pineapple mixer.

22. The plasticizing screw of claim 18, wherein the melt sub-section comprises a first melt sub-section and a second melt sub-section configured to have different melting operations, and the length of the second melt sub-section is between 60% and 67% of the length of the melt sub-section.

23. The plasticizing screw of claim 22, wherein the length of the second melt sub-section is between 30% and 34% of the effective length of the plasticizing screw.

24. The plasticizing screw of claim 22, wherein the second melt sub-section is configured to operate using a dispersive melt effect.

25. The plasticizing screw of claim 22, wherein the second melt sub-section includes a wave zone having a plurality of convex ridges alternately offset relative to the root of the screw.

26. A plasticizing screw for a molding machine, the plasticizing screw comprising: Feeding section, Melting zone, and The mixing section includes a first mixing sub-section and a second mixing sub-section, wherein the first mixing sub-section is configured to operate by dispersion mixing and its length is 8-10% of the effective length of the plasticizing screw.

27. The plasticizing screw of claim 26, wherein the length of the mixing section exceeds 13% of the effective length of the plasticizing screw.

28. The plasticizing screw according to claim 27, wherein the length of the mixing section is 14-34% of the effective length of the plasticizing screw.

29. The plasticizing screw of claim 26, wherein the first mixing sub-section comprises a spiral mixer.

30. The plasticizing screw of claim 26, wherein the melt sub-section comprises a first melt sub-section and a second melt sub-section configured to have different melting operations, and the length of the second melt sub-section is between 37% and 67% of the length of the melt sub-section.

31. The plasticizing screw according to claim 30, wherein the length of the second melt sub-section is between 6% and 23% of the effective length of the plasticizing screw.

32. The plasticizing screw of claim 31, wherein the second melt sub-section is configured to operate using a dispersive melt effect.

33. The plasticizing screw of claim 31, wherein the second melt sub-section includes a wave zone having a plurality of convex ridges alternately offset relative to the root of the screw.

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