CN110126193B - Ultrahigh molecular weight polyethylene choked flow type porous injection molding nozzle - Google Patents
Ultrahigh molecular weight polyethylene choked flow type porous injection molding nozzle Download PDFInfo
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- CN110126193B CN110126193B CN201910409535.7A CN201910409535A CN110126193B CN 110126193 B CN110126193 B CN 110126193B CN 201910409535 A CN201910409535 A CN 201910409535A CN 110126193 B CN110126193 B CN 110126193B
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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
- B29C45/20—Injection nozzles
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Abstract
The invention relates to a flow-blocking type porous injection molding nozzle for ultrahigh molecular weight polyethylene, which is provided with a metal nozzle body, wherein a melt flow passage in the metal nozzle body sequentially consists of a slotted cylindrical flow passage, a stepped variable-diameter cylindrical flow passage and a small-caliber porous cylindrical finish mold in the flow direction. The structure of slotting, stepped diameter variation and the like interferes the flow of the ultrahigh molecular weight polyethylene melt, and the small-caliber porous cylindrical neck mold generates a high shearing action under the condition of reducing the flow resistance, so that the ultrahigh molecular weight polyethylene melt is promoted to be seriously cracked to form ideal fine powdery particles required by the preparation of functional materials.
Description
Technical Field
The invention relates to the technical field of injection molding machine equipment, in particular to a flow-blocking type porous injection molding nozzle suitable for ultrahigh molecular weight polyethylene injection.
Background
The injection nozzle is one of the important parts for injection molding machine to realize injection molding. The runner of an injection molding nozzle is generally composed of a tapered runner with a smooth transition and a single-hole cylindrical die for ejecting the polymer melt from the nozzle runner at high speed. Ultra-high molecular weight polyethylene (linear polyethylene having a viscosity average molecular weight of more than 150 ten thousand) is susceptible to melt fracture under high shear, and when the shear rate is sufficiently high, severe melt fracture occurs to form powdery particles. In the preparation of some ultrahigh molecular weight polyethylene functional materials, the ultrahigh molecular weight polyethylene melt is required to be formed into powder particles by injection through a nozzle, and the finer the particles, the better. In order to obtain fine ultra-high molecular weight polyethylene powder particles, it is beneficial to reduce the nozzle orifice diameter to increase the shearing action (promote melt fracture), however, reducing the nozzle orifice diameter will significantly increase the flow resistance at the time of injection, and since ultra-high molecular weight polyethylene has very poor flowability (almost no flowability), a smaller nozzle orifice diameter will result in the need to use very high injection pressures for injection of ultra-high molecular weight polyethylene. On the other hand, the invention discovers in research that the forming of the superfine particles is facilitated by intensifying the fracture degree of the melt by disturbing the flowing state of the ultrahigh molecular weight polyethylene melt, and the conventional injection nozzle runner generally adopts a larger-caliber and smooth runner structure to promote the smooth flowing of the melt, which is not favorable for the fracture forming of the ultrahigh molecular weight polyethylene melt. Therefore, it is difficult to obtain desired ultra-high molecular weight polyethylene fine particles using a conventional injection nozzle.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a high molecular weight polyethylene flow-blocking type porous injection molding nozzle, and ultrahigh molecular weight polyethylene fine particles can be formed by injection through the nozzle.
In order to achieve the purpose, the invention adopts the following scheme:
the utility model provides a porous injection molding nozzle of ultrahigh molecular weight polyethylene choked flow, includes the metal nozzle body, and metal nozzle body center has the fuse-element runner that runs through metal nozzle body both ends, and its characterized in that, the fuse-element runner includes fluting cylinder runner, cascaded variable diameter cylinder runner and the porous cylinder bush of small-bore in proper order along the fuse-element flow direction and constitutes.
The slotted cylindrical flow passage consists of a cylindrical flow passage positioned in the center and a reticular groove arranged on the periphery of the cylindrical flow passage.
The reticular groove comprises a plurality of radial annular grooves and a plurality of axial straight grooves, the radial annular grooves are uniformly distributed in the length direction of the cylindrical flow channel at intervals, the axial straight grooves are uniformly distributed on the circumference of the cylindrical flow channel, and the radial annular grooves and the axial straight grooves are arranged in a crossed manner. Since the radial annular grooves and the axial straight grooves are arranged in a net shape in a crossing manner, the flow of the ultrahigh molecular weight polyethylene melt in this section is disturbed by the axial intermittent obstruction and the radial flow splitting of the net-shaped grooves, but on the other hand, the flow resistance is increased.
The radial annular groove and the axial straight groove are rectangular grooves, semicircular grooves or V-shaped grooves.
The stepped variable-diameter cylindrical flow passage comprises a plurality of sections of cylindrical flow passages, and the diameters of inner holes of the plurality of sections of cylindrical flow passages are reduced step by step along the flow direction. The flow of the ultrahigh molecular weight polyethylene melt is interrupted intermittently at the respective ring-shaped cross-sections of varying diameter, thereby causing a pulsating disturbance, but on the other hand, an increase in flow resistance is caused.
The small-caliber porous cylindrical finish mold is composed of at least three small-caliber cylindrical holes, and the small-caliber cylindrical holes are uniformly distributed in the radial direction of the small-caliber porous cylindrical finish mold.
The diameter of the small-caliber cylindrical hole is 0.5-2.5 mm. Because the bore of small-bore cylinder hole is less, can provide the high shear rate and break with the fuse-element when aggravating the injection of ultra-high molecular weight polyethylene, on the other hand, compare with only setting up small-bore single pore bush, a plurality of small-bore mouth moulds of evenly distributed for the total effective sectional area increase of bush runner, thereby can reduce by the resistance increase that fluting cylinder runner, cascaded variable diameter cylinder runner and the porous cylinder bush of small-bore arouse jointly, make the general flow resistance decline, help reducing the injection pressure that the injection is required.
The flow-blocking type porous injection molding nozzle for the ultrahigh molecular weight polyethylene is applied to the ultrahigh molecular weight polyethylene and the mixture thereof.
Compared with the prior art, the invention has the beneficial effects that:
through set up vertically and horizontally staggered's netted radial ring channel, the straight groove of axial that distributes at the metal nozzle runner, hole diameter is the cylinder runner of cascaded reduction, makes the steady flow state of ultra high molecular weight polyethylene fuse-element receive interference and destruction to aggravate the emergence that the fuse-element broke. Since the nozzle die consists of a plurality of small bore dies, a high shear rate can be provided to promote severe cracking of the ultra high molecular weight polyethylene. The arrangement of a plurality of dies increases the sectional area of the total flow passage, so that the injection pressure required by injection can be reduced. By the above-mentioned flow disturbance and high shear action, desired ultra-high molecular weight polyethylene fine particles can be obtained by nozzle injection.
Drawings
The following is further described with reference to the accompanying drawings:
FIG. 1 is a schematic structural view of an injection molding nozzle according to the present invention;
FIG. 2 is a cross-sectional view of section A-A of FIG. 1;
FIG. 3 is an enlarged schematic cross-sectional view I of a radial ring groove and an axial straight groove;
FIG. 4 is an enlarged schematic cross-sectional view II of the radial ring groove and the axial straight groove;
FIG. 5 is an enlarged schematic cross-sectional view III of the radial ring groove and the axial straight groove;
FIG. 6 is a cross-sectional view of section B-B of FIG. 1;
FIG. 7 is a schematic diagram I of the arrangement mode of the small-caliber porous cylindrical neck mold of the invention;
FIG. 8 is a schematic diagram II of the arrangement mode of the small-caliber porous cylindrical neck mold of the invention;
fig. 9 is a Scanning Electron Microscope (SEM) photograph of the microstructure of the ultra-high molecular weight polyethylene powdery particles obtained in example 1;
fig. 10 is a Scanning Electron Microscope (SEM) photograph of the microstructure of the ultra-high molecular weight polyethylene powdery particles obtained in the comparative example.
Wherein:
1-a metallic nozzle body; 1 a-a slotted cylindrical flow channel; 1a 1-radial annular groove; 1a 2-axial straight groove; 1a 3-cylindrical flow channel; 1b, a stepped variable-diameter cylindrical flow channel; 1 c-a small-caliber porous cylindrical opening die; 1 d-thread; g, a rectangular groove; m-a semicircular groove; n-V-shaped groove.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As shown in fig. 1, the injection molding nozzle comprises a metal nozzle body 1, a melt flow channel penetrating through two ends of the metal nozzle body 1 is arranged in the center of the metal nozzle body 1, the melt flow channel sequentially comprises a slotted cylindrical flow channel 1a, a stepped variable-diameter cylindrical flow channel 1b and a small-caliber porous cylindrical neck ring mold 1c according to the melt flowing direction, the slotted cylindrical flow channel 1a is located at the opening end of the metal nozzle body 1, the small-caliber porous cylindrical neck ring mold 1c is located at the outlet end of the metal nozzle body 1, and the stepped variable-diameter cylindrical flow channel 1b is located between the slotted cylindrical flow channel 1a and the small-caliber porous cylindrical neck ring mold 1 c.
The outer wall of the inlet end of the metal nozzle body 1 is provided with threads 1d, and the threads 1d are used for being connected with the tail end of a machine barrel of an injection molding machine.
As shown in fig. 1-2, the slotted cylindrical flow passage 1a is composed of a cylindrical flow passage 1a3 located at the center, and a plurality of radial annular grooves 1a1 and a plurality of axial straight grooves 1a2 arranged on the outer circumference of the cylindrical flow passage 1a3, wherein the plurality of radial annular grooves 1a1 are uniformly distributed at intervals in the length direction of the cylindrical flow passage 1a3, and the plurality of axial straight grooves 1a2 are uniformly distributed in the circumferential direction of the cylindrical flow passage 1a 3.
The radial annular groove 1a1 and the axial straight groove 1a2 may have various cross sections, and as shown in fig. 3 to 5, the cross sections of the radial annular groove 1a1 and the axial straight groove 1a2 may be rectangular grooves g, semicircular grooves m, or V-shaped grooves n.
As shown in fig. 1, the stepped variable diameter cylindrical runner 1b includes a plurality of cylindrical runners whose inner hole diameters are reduced stepwise in the direction of the melt flow.
The small-caliber multi-hole cylindrical die 1c is provided with at least three small-caliber cylindrical holes which are uniformly distributed in the radial direction, the arrangement number of the small-caliber cylindrical holes can be 5 (as shown in fig. 6), 4 (as shown in fig. 7) or 3 (as shown in fig. 8), and the arrangement positions of the small-caliber cylindrical holes are respectively shown in fig. 6 to 8. The larger the number of small-bore cylinders, the larger the flow resistance decreases.
Example 1
By adopting the nozzle, a melt flow channel in the metal nozzle body 1 sequentially consists of a slotted cylindrical flow channel 1a, a stepped variable-diameter cylindrical flow channel 1b and a small-caliber multi-hole cylindrical finish mold 1c along the flowing direction. The slotted cylindrical runner 1a comprises 6 radial annular grooves 1a1 and 4 axial straight grooves 1a2, the sections of the radial annular grooves 1a1 and the axial straight grooves 1a2 both adopt rectangular grooves g, and the small-caliber multi-hole cylindrical neck ring mold 1c is formed by 5 small-caliber cylindrical neck rings with the calibers of phi 1mm according to the arrangement mode shown in figure 6. The viscosity average molecular weight of the ultra-high molecular weight polyethylene is 500 ten thousand, and the average particle size of the ultra-high molecular weight polyethylene powder particles obtained by injection through the nozzle is 2.45mm under the conditions that the temperature at the tail end of the machine cylinder is 260 ℃, the injection pressure is 60MPa and the injection speed is 42 mm/s.
Comparative example
A common injection molding nozzle is adopted, and a melt flow passage of the common injection molding nozzle consists of a section of smooth tapered flow passage and a section of single-hole cylindrical neck mold. The aperture of the inlet of the tapered runner is phi 13mm, and the aperture of the nozzle (a single-hole cylindrical die) is phi 1 mm. The viscosity average molecular weight of the ultra-high molecular weight polyethylene is 500 ten thousand, and the average particle size of the ultra-high molecular weight polyethylene powder particles obtained by injection through the nozzle is 2.52mm under the conditions that the temperature at the tail end of the machine cylinder is 260 ℃, the injection pressure is 60MPa and the injection speed is 42 mm/s.
By comparing example 1 with the comparative example, the average particle diameter of the ultra-high molecular weight polyethylene powdery particles obtained in example 1 was 2.45mm, which was smaller than the average particle diameter of 2.52mm obtained in the comparative example. On the other hand, Scanning Electron Microscope (SEM) photographic analysis of the particle microstructure showed that the particle morphology obtained in example 1 (fig. 9) had a contour shape of microscopic particles (powder particles composed of a large number of finer microscopic particles) closer to a desired spherical shape and a more uniform internal structure than the microscopic particle morphology obtained in comparative example (fig. 10). This indicates that the desired effect is obtained using the nozzle of the present invention.
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that are not thought of through the inventive work should be included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope defined by the claims.
Claims (6)
1. A flow-blocking type porous injection molding nozzle for ultrahigh molecular weight polyethylene comprises a metal nozzle body, wherein a melt flow channel penetrating through two ends of the metal nozzle body is arranged in the center of the metal nozzle body;
the slotted cylindrical flow passage consists of a cylindrical flow passage positioned in the center and a reticular groove arranged at the periphery of the cylindrical flow passage;
the reticular groove comprises a plurality of radial annular grooves and a plurality of axial straight grooves, the radial annular grooves are uniformly distributed in the length direction of the cylindrical flow channel at intervals, the axial straight grooves are uniformly distributed on the circumference of the cylindrical flow channel, and the radial annular grooves and the axial straight grooves are arranged in a crossed manner.
2. The ultrahigh molecular weight polyethylene bluff type multi-orifice injection molding nozzle of claim 1, wherein: the radial annular groove and the axial straight groove are rectangular grooves, semicircular grooves or V-shaped grooves.
3. The ultrahigh molecular weight polyethylene bluff type multi-orifice injection molding nozzle of claim 1, wherein: the stepped variable-diameter cylindrical flow passage comprises a plurality of sections of cylindrical flow passages, and the diameters of inner holes of the plurality of sections of cylindrical flow passages are reduced step by step along the flow direction.
4. The ultrahigh molecular weight polyethylene bluff type multi-orifice injection molding nozzle of claim 1, wherein: the small-caliber multi-hole cylindrical finish mold consists of at least three small-caliber cylindrical holes, and the small-caliber cylindrical holes are uniformly distributed in the radial direction of the small-caliber multi-hole cylindrical finish mold.
5. The ultrahigh molecular weight polyethylene bluff type multi-orifice injection molding nozzle of claim 4, wherein: the diameter of the small-caliber cylindrical hole is 0.5-2.5 mm.
6. Use of an ultra high molecular weight polyethylene bluff body multi-orifice injection molding nozzle as claimed in any one of claims 1 to 5 on ultra high molecular weight polyethylene and mixtures thereof.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201910409535.7A CN110126193B (en) | 2019-05-17 | 2019-05-17 | Ultrahigh molecular weight polyethylene choked flow type porous injection molding nozzle |
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| CN201910409535.7A CN110126193B (en) | 2019-05-17 | 2019-05-17 | Ultrahigh molecular weight polyethylene choked flow type porous injection molding nozzle |
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| CN110126193B true CN110126193B (en) | 2020-07-24 |
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| CN113153732B (en) * | 2021-05-31 | 2024-06-07 | 宝鸡航天动力泵业有限公司 | Reciprocating plunger type injection pump fluid end |
| CN114368106B (en) * | 2021-12-31 | 2022-11-15 | 北京化工大学 | Injection molding method of ultra-high molecular weight polyethylene microporous filter material |
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| CN105397980B (en) * | 2015-12-09 | 2017-12-19 | 荣昌精密机械(苏州)有限公司 | The nozzle of structure optimization on a kind of injection machine |
| CN105751434B (en) * | 2016-04-15 | 2018-02-16 | 浙江大学宁波理工学院 | The nozzle of injection machine |
| DE102017107443A1 (en) * | 2017-04-06 | 2018-10-11 | Günther Heisskanaltechnik Gmbh | Insert for use in an injection molding nozzle and injection molding nozzle with such an insert |
| CN208006139U (en) * | 2018-03-29 | 2018-10-26 | 深圳市新泰兴精密科技有限公司 | A kind of porous, shaped nozzle of injection molding machine platypelloid type |
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