CN111823523B - Bamboo joint type back mixing screw rod for enhancing heat transfer and mixing - Google Patents
Bamboo joint type back mixing screw rod for enhancing heat transfer and mixing Download PDFInfo
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- CN111823523B CN111823523B CN202010667104.3A CN202010667104A CN111823523B CN 111823523 B CN111823523 B CN 111823523B CN 202010667104 A CN202010667104 A CN 202010667104A CN 111823523 B CN111823523 B CN 111823523B
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- back mixing
- mixing
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- barrier wall
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/46—Means for plasticising or homogenising the moulding material or forcing it into the mould
- B29C45/58—Details
- B29C45/60—Screws
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/50—Details of extruders
- B29C48/505—Screws
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
- Extrusion Moulding Of Plastics Or The Like (AREA)
Abstract
The invention discloses a bamboo joint type back mixing screw rod for enhancing heat transfer and mixing, which belongs to the technical field of polymer processing and forming, and comprises a screw thread section and a back mixing element, wherein the back mixing element comprises a barrier wall and a plurality of notches, one surface of the barrier wall along the flow direction is a back mixing surface in the process of forward conveying of a material, the back mixing surface is a convergent curved surface with curvature change from the bottom to the top of the barrier wall, the back mixing surface can enable the material to generate rolling countercurrent in the conveying process, and a part of fluid flows in a reverse direction and is fully mixed on the cross section of a flow channel; and a plurality of uniformly distributed gaps are formed at the top of the barrier wall. The invention improves the mixing and plasticizing performance of the screw, so that the product has better service performance and surface quality, forms a convergent channel, strengthens the stretching effect, avoids generating larger shearing force in the processing process and increases the processing flexibility of various materials.
Description
Technical Field
The invention belongs to the technical field of polymer processing and forming, and particularly relates to a bamboo joint type back mixing screw for enhancing heat transfer and mixing.
Background
The screw is a core component of a polymer processing and forming device (an extruder, an injection molding machine and the like), and the mixing and plasticizing performance of the screw determines the quality and the production cost of a final product, so that the screw has important significance for optimizing the structure of the screw. In particular to special product fields, higher requirements are put on the screw. For example, for cellulose-reinforced bio-based nanocomposites, a low shear, high mixing screw is required, and at the same time, thermal decomposition of the filled cellulose and other nanomaterials is prevented, which is very important for temperature control and thermal management of the entire plasticizing process.
The invention discloses a high-shear high-mixing plasticizing screw, which is mainly designed by a special structure of a melting section and a mixing section with double threads to improve the shearing and plasticizing effects of the screw, but has a relatively complex structure and high processing cost, and materials are easily decomposed under the action of high shearing force, so that the application range of the screw is limited.
Therefore, in the field of polymer processing and forming technology, there is still a need for research and improvement on a low-shear, high-mixing screw, which is also a research focus and emphasis in the field of polymer processing and forming technology at present, and is the starting point for the completion of the present invention.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is as follows: the bamboo joint type back mixing screw for enhancing heat transfer and mixing is simple to process, low in shearing, high in adaptability to materials and excellent in mixing and plasticizing performance, efficient mixing and heat transfer of the screw under low shearing force are achieved, and the working condition that materials need low shearing and are easy to decompose is met.
In order to solve the technical problems, the technical scheme of the invention is as follows: a bamboo joint type back mixing screw rod for enhancing heat transfer and mixing comprises a threaded section and a back mixing element, wherein the back mixing element comprises a barrier wall and a plurality of openings, the barrier wall is integrally bamboo joint-shaped, the axis of the back mixing element is collinear with the axis of the threaded section, and the maximum diameter of the back mixing element is equivalent to the major diameter of the threaded section; in the process of forward conveying of materials, one surface of the barrier wall along the flow direction is a back mixing surface, the back mixing surface is a convergence curved surface with curvature change from the bottom to the top of the barrier wall, the back mixing surface can enable the materials to generate rolling countercurrent in the conveying process, and a part of fluid flows in a reverse direction and is fully mixed on the cross section of the flow passage; and a plurality of uniformly distributed gaps are formed at the top of the barrier wall.
As an improvement, the longitudinal section of the back mixing surface is a part of an ellipse or a part of a circle with gradually-increased curvature.
As a further improvement, the radial length of the elliptic curved surface higher than the bottom diameter of the thread section is defined as a, the axial length of the elliptic curved surface is defined as b, and the ratio of the a to the b is not less than 0.5.
As an improvement, the included angle between the tangent line of the curve at the top end of the longitudinal section line of the back mixing surface and the positive direction of the flow axis is not less than 90 degrees.
As a modification, the shape of the gap is a semicircle or a rectangle with round corners.
As an improvement, an auxiliary conveying screw thread is further arranged on the back mixing element, the major diameter of the auxiliary conveying screw thread is not larger than that of the back mixing element, and the auxiliary conveying screw thread does not interfere with the notch; the number of the heads of the auxiliary conveying threads is single or multiple.
As an improvement, the back mixing element is arranged in the compression section or the metering section of the screw.
As an improvement, there are at least two said back mixing elements, and the size of said gaps of said back mixing elements decreases gradually along the flowing direction, and the number of said gaps increases gradually.
As an improvement, at least two back mixing elements are arranged, and the back mixing elements are continuously arranged or are arranged at intervals with the thread sections; the phases of the gaps opened by the adjacent back mixing elements are periodically aligned or periodically staggered or non-periodically staggered.
As an improvement, the back mixing element is integrally processed with the thread section; or made into a building block type, positioned by a mandrel and assembled.
After the technical scheme is adopted, the invention has the beneficial effects that:
the heat transfer and mixing enhanced bamboo joint type back mixing screw rod is characterized in that a back mixing element is designed, the back mixing element comprises a barrier wall with a back mixing surface, the back mixing surface is a convergent curved surface with curvature change from the bottom to the top of the barrier wall, so that materials generate rolling countercurrent in the conveying process, the mixing and plasticizing uniformity is improved, the plasticization is more sufficient, products with higher service performance and surface quality are obtained, a convergent flow channel is formed at the same time, the stretching effect is enhanced, larger shearing force is avoided, and the processing flexibility of various materials is increased; and the screw is simple to process, so that the high-efficiency mixing and heat transfer of the screw under low shearing force are realized, and the working condition that the material needs low shearing and is easy to decompose is met. Because the back mixing element is also provided with the notch, a small part of materials pass through the back mixing element, and the problem that the forward conveying resistance of the materials is large due to overlarge pressure difference between two sides of the barrier wall is avoided.
Because the longitudinal section of the back mixing surface is a part of an ellipse or a part of a circle with gradually-increased curvature, the radial length of the elliptic curved surface higher than the bottom diameter of the thread section is defined as a, and the axial length of the elliptic curved surface is defined as b, the ratio of a to b is not less than 0.5, and the tumbling and countercurrent of materials are more facilitated.
Because the included angle between the curve tangent line at the top end of the longitudinal section line of the back mixing surface and the positive direction of the flow axis is not less than 90 degrees, the speed is ensured to have a component opposite to the flow direction so as to realize physical back mixing.
Because the shape of the notch is semicircular or rectangular with round corners, the occurrence of material accumulation can be effectively avoided.
Because the back mixing element is also provided with the auxiliary conveying screw thread, the conveying capacity of the back mixing element is improved through the auxiliary conveying screw thread.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.
The structures, ratios, sizes, and the like shown in the present specification are only used for matching with the contents disclosed in the specification, so that those skilled in the art will understand and read the present invention, and do not limit the conditions for implementing the present invention, so that the present invention has no technical essence, and any modifications of the structures, changes of the ratio relationships, or adjustments of the sizes, should still fall within the scope covered by the technical contents disclosed in the present invention without affecting the efficacy and the achievable purpose of the present invention.
FIG. 1 is a schematic view of a three-dimensional structure of a heat transfer and mixing enhancing slub-type back mixing screw provided by an embodiment of the invention;
FIG. 2 is a schematic perspective view of a back mixing element according to an embodiment of the present invention;
FIG. 3 is a schematic view of the longitudinal cross-sectional flow direction of a back mixing element in an embodiment of the present invention;
FIG. 4 is a schematic perspective view of a back mixing screw with an auxiliary conveying screw according to an embodiment of the present invention;
in the figure: 1. a threaded segment; 2. a back mixing element; 21. a barrier wall; 211. back mixing the dough; 22. opening; 23. auxiliary conveying screw threads;
2-1 back mixing elements with the number of openings being 12; 2-2 back mixing elements with the number of the openings being 16; 2-3 back mixing elements with the number of the gaps being 20.
Detailed Description
The present invention is described in terms of particular embodiments, other advantages and features of the invention will become apparent to those skilled in the art from the following disclosure, and it is to be understood that the described embodiments are merely exemplary of the invention and that it is not intended to limit the invention to the particular embodiments disclosed. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
In the present specification, the terms "front", "rear", "left", "right", "inner", "outer" and "middle" are used for the sake of clarity only, and are not intended to limit the scope of the present invention, and changes or modifications of the relative relationship between the terms and the corresponding parts are also regarded as the scope of the present invention without substantial changes in the technical contents.
As shown in fig. 1, the heat transfer and mixing enhancement bamboo joint type back mixing screw comprises a screw thread section 1 and back mixing elements 2, wherein the screw thread section 1 is a conventional screw thread element, the back mixing elements 2 can be arranged at different positions of the screw, such as a compression section, a metering section and the like of the screw according to the processing purpose, and the back mixing elements 2 are sequentially arranged in a bamboo joint type overlapping manner.
As shown in fig. 1 and fig. 2, the back mixing element 2 comprises a barrier wall 21 and a plurality of gaps 22, the barrier wall 21 is in a bamboo joint shape as a whole, the axis of the back mixing element 2 is collinear with the axis of the threaded section 1, and the maximum diameter of the back mixing element 2 is equivalent to the major diameter of the threaded section 1. In the process of forward conveying of materials, one surface along the flowing direction in the barrier wall 21 is a back mixing surface 211, the back mixing surface 211 is a convergence curved surface with curvature change from the bottom to the top of the barrier wall 21, the curvature of the back mixing surface 211 can be various, the shape which is most beneficial to rolling and counter-flowing of the materials is processed according to actual processes, the back mixing surface 211 can enable the materials to generate rolling and counter-flowing in the conveying process, and part of the fluid flows in the reverse direction and is fully mixed on the cross section of a flow channel. The top of the barrier wall 21 is provided with a plurality of notches 22 which are uniformly distributed, so that a small part of materials can pass through, and the problem that the forward conveying resistance of the materials is large due to overlarge pressure difference at two sides of the barrier wall 21 is avoided.
The longitudinal cross-sectional shape of the back mixing surface 211 is a part of an ellipse or a part of a circle having a gradually increasing curvature. Of course, the back mixing surface 211 may be formed in other shapes that facilitate tumbling and counter-flow. The curvature of the elliptic curved surface can be various, and preferably, as shown in fig. 3, the radial length of the elliptic curved surface higher than the bottom diameter of the threaded section is defined as a, and the axial length of the elliptic curved surface is defined as b, and then the ratio of a to b is not less than 0.5, so that the materials pass through the back mixing surface 211 of the back mixing element 2, the tumbling and reverse flow are facilitated, and the mixing and plasticizing of each component are more uniform and complete.
The angle alpha between the tangent to the curve at the top of the longitudinal section line of the back-mixing surface 211 and the positive direction of the flow axis is not less than 90 deg., thus ensuring that the velocity has a component opposite to the flow direction to realize physical back-mixing.
The shape of the opening 22 made by the back mixing element 2 can be various, preferably, the shape of the opening 22 is a semicircle or a rectangle with round corners, the size and the number of the openings 22 can also be various, the pressure of the placing position of the back mixing element 2 is required to be ensured within the range of proper processing, and the situation of material accumulation does not occur.
In order to improve the conveying capacity of the back mixing element 2, as shown in fig. 4, an auxiliary conveying screw thread 23 is further arranged on the back mixing element 2, and the major diameter of the auxiliary conveying screw thread 23 is not larger than that of the back mixing element 2 and does not interfere with the gap; the profile of the auxiliary conveying screw 23 is the same as that of a conventional screw, and the number of the heads of the auxiliary conveying screw 23 is single or multiple.
Preferably, there are at least two back mixing elements 2, and the size of the gaps 22 of different back mixing elements 2 decreases gradually along the flow direction, and the number of gaps 22 increases gradually. The change in size of the gap 22 is not limited to radial or circumferential. As shown in FIG. 4, 2-1 is the back mixing element with the number of openings of 12, 2-2 is the back mixing element with the number of openings of 16, and 2-3 is the back mixing element with the number of openings of 20.
When a plurality of back mixing elements 2 are provided, the shape (such as the structure and number of the gaps 22, the curvature of the back mixing surface 211, the overall length, etc.) of each back mixing element 2 can be different, and the arrangement mode can be various, and preferably, the back mixing elements 2 are arranged continuously or the back mixing elements 2 and the thread sections 1 are arranged at intervals. The phase of the slits 22 opened by the adjacent back mixing elements 2 can be various, and preferably, the phase of the slits 22 opened by the adjacent back mixing elements 2 is periodically aligned or periodically staggered or non-periodically staggered, and the staggered angle can be various.
The back mixing element 2 can be integrally processed with the thread section 1; or made into a building block type, positioned by a mandrel and assembled.
In summary, the heat transfer and mixing enhanced bamboo joint type back mixing screw provided by the embodiment of the invention enables materials to generate rolling countercurrent in the conveying process through the back mixing element, improves the mixing and plasticizing uniformity, enables the plasticizing to be more sufficient, obtains products with higher service performance and surface quality, forms a convergent channel, enhances the stretching effect, avoids larger shearing force, and increases the processing flexibility of various materials; and the screw is simple to process, the efficient mixing and heat transfer of the screw under low shearing force are realized, and the working condition that the material needs low shearing and is easy to decompose is met.
Although the invention has been described in detail above with reference to a general description and specific examples, it will be apparent to one skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.
Claims (8)
1. The bamboo joint type back mixing screw rod for enhancing heat transfer and mixing is characterized by comprising a threaded section and a back mixing element, wherein the back mixing element comprises a barrier wall and a plurality of openings, the barrier wall is integrally in a bamboo joint shape, the axis of the back mixing element is collinear with the axis of the threaded section, and the maximum diameter of the back mixing element is equivalent to the major diameter of the threaded section; in the process of forward conveying of materials, one surface of the barrier wall along the flow direction is a back mixing surface, the back mixing surface is a convergent curved surface with curvature change from the bottom to the top of the barrier wall, the back mixing surface can enable the materials to generate rolling countercurrent in the conveying process, and a part of fluid generates reverse flow and is fully mixed on the cross section of the flow passage; the top of the barrier wall is provided with a plurality of uniformly distributed gaps;
the longitudinal section of the back mixing surface is a part of an ellipse or a part of a circle with gradually-increased curvature;
and defining the radial length of the elliptic curved surface higher than the bottom diameter of the thread section as a, and the axial length of the elliptic curved surface as b, wherein the ratio of a to b is not less than 0.5.
2. The heat transfer and mixing enhancement slub type back mixing screw according to claim 1, wherein the included angle between the tangent line of the curve at the top end of the longitudinal section line of the back mixing surface and the positive direction of the flow axis is not less than 90 degrees.
3. The heat transfer and mixing enhancement bamboo joint type back mixing screw rod as claimed in claim 1, wherein the shape of the gap is semicircular or rectangular with round corners.
4. The heat transfer and mixing enhancement bamboo joint type back mixing screw rod according to claim 1, wherein an auxiliary conveying screw thread is further arranged on the back mixing element, the major diameter of the auxiliary conveying screw thread is not larger than that of the back mixing element, and the auxiliary conveying screw thread does not interfere with the notch; the number of the heads of the auxiliary conveying threads is single or multiple.
5. The heat transfer and mixing enhancement slub type back mixing screw according to claim 1, wherein the back mixing element is arranged at a compression section or a metering section of the screw.
6. The heat transfer and mixing enhancement slub type back mixing screw according to claim 1, wherein the number of the back mixing elements is at least two, the sizes of the gaps of the back mixing elements are gradually reduced along different flowing directions, and the number of the gaps is gradually increased.
7. The heat transfer and mixing enhancement bamboo joint type back mixing screw rod according to claim 1, wherein the number of the back mixing elements is at least two, and the back mixing elements are arranged continuously or the back mixing elements and the thread sections are arranged at intervals; the phases of the gaps opened by the adjacent back mixing elements are periodically aligned or periodically staggered or non-periodically staggered.
8. The heat transfer and mixing enhancement bamboo joint type back mixing screw rod according to claim 1, wherein the back mixing element and the thread section are processed into a whole; or made into a building block type, positioned by a mandrel and assembled.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010667104.3A CN111823523B (en) | 2020-07-13 | 2020-07-13 | Bamboo joint type back mixing screw rod for enhancing heat transfer and mixing |
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| CN202010667104.3A CN111823523B (en) | 2020-07-13 | 2020-07-13 | Bamboo joint type back mixing screw rod for enhancing heat transfer and mixing |
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| CN111823523B true CN111823523B (en) | 2022-12-13 |
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| CN114907657A (en) * | 2022-05-31 | 2022-08-16 | 浙江南洋科技有限公司 | Reactive extrusion method biaxially oriented polyvinyl alcohol film and preparation method thereof |
| CN116175931A (en) * | 2023-04-28 | 2023-05-30 | 广东工业大学 | Wheel-shaped stretching screw for double-screw extruder and meshing method |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106470818A (en) * | 2014-07-11 | 2017-03-01 | 科思创德国股份有限公司 | There is the hybrid element of the dispersion effect of improvement |
| CN107139425A (en) * | 2017-07-11 | 2017-09-08 | 广东轻工职业技术学院 | Strongly tensile differential multi-screw extruder in the same direction and its processing method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20110133355A1 (en) * | 2007-10-19 | 2011-06-09 | Kotaro Takita | Extruder Having Dual Mixing Stages And Process For Preparing A Mixture Of Polymer And Diluent |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106470818A (en) * | 2014-07-11 | 2017-03-01 | 科思创德国股份有限公司 | There is the hybrid element of the dispersion effect of improvement |
| CN107139425A (en) * | 2017-07-11 | 2017-09-08 | 广东轻工职业技术学院 | Strongly tensile differential multi-screw extruder in the same direction and its processing method |
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