CN113021886B - A 3D printing nozzle structure that realizes the supercooling of continuous fiber self-reinforced composites - Google Patents

Abstract

A 3D printing nozzle structure for realizing the supercooling of continuous fiber self-reinforced composite materials, including a liquefier, a nozzle is connected to the lower end of the liquefier, a matrix phase enters from the upper end of the liquefier, and is heated to a molten state by the liquefier, enters the nozzle, and is liquefied. During the process from the nozzle to the nozzle, the temperature is lowered to below the melting point of the matrix phase and does not crystallize, forming a supercooled melt; the side of the nozzle is provided with fiber holes, and the reinforcing phase enters the supercooled melt of the matrix phase through the fiber holes, and the reinforcing phase wraps the matrix phase. It is extruded and cooled from the nozzle and then solidified and formed; the invention utilizes the supercooling degree of the polymer, and introduces the reinforcing phase through the fiber hole during the 3D printing cooling process. The large shape is complex, the molding cycle is short, the cost is low, and the production efficiency is high.

Description

3D printing nozzle structure for supercooled forming of continuous fiber self-reinforced composites

technical field

The invention relates to the technical field of 3D printing of continuous fiber reinforced composite materials, in particular to a 3D printing nozzle structure for realizing supercooled forming of continuous fiber self-reinforced composite materials.

Background technique

The continuous fiber self-reinforced composite material (single polymer composite material) is a composite material in which the matrix and the reinforcing phase are the same polymer or the same family of polymers. Compared with traditional fiber reinforced composite materials, the advantage of fiber self-reinforced composite materials is that two materials with the same chemical composition and different physical properties are compounded together without adding modified fibers, and excellent interface bonding strength can be obtained. The product has low density and high recycling rate.

The continuous fiber self-reinforced composite material forming methods include fiber hot pressing method, film embedding hot pressing method, sandwich hot pressing method, filament winding hot pressing method and so on. For the fiber hot pressing method and the filament winding hot pressing method, the hot pressing temperature is raised above the melting point of the fiber during the forming process, so that the surface layer of the fiber is melted and the interior is kept oriented, and the melted part is then solidified into the matrix phase. The disadvantage of this method is the processing The window is too narrow, and the temperature control during the processing is extremely strict. Select the appropriate hot-pressing temperature. If the hot-pressing temperature is too low, the surface fibers will not be fully melted, and a relatively complete matrix phase cannot be formed; The fiber melts more and the fiber content decreases, which ultimately leads to an insignificant enhancement of mechanical properties; and the processing temperature range is often controlled at 1 to 2 degrees. The other type of sandwich hot pressing method and film embedding hot pressing method requires a sufficiently large melting point difference between the matrix phase and the reinforcement phase to achieve the effect of melting the matrix phase but not the reinforcement phase. The body belongs to the same polymer material, the difference in melting temperature is small, and the difference in melting point is usually within 5 degrees. Under the conditions of conventional polymer processing melting temperature, the reinforcement in the matrix often also produces thermal damage, thereby reducing the reinforcement phase. The mechanical properties make the reinforcing phase unable to play a reinforcing role.

The above forming methods all have the disadvantages of a narrow processing temperature window and thermal damage to the reinforcing phase, and the hot pressing method has the defects of small size and simple shape, long forming cycle, high cost and low production efficiency, so increase the fiber self-reinforcing. The processing temperature window of composite materials is the core issue in the development of self-reinforced composite materials, and it is also a difficult research point for self-reinforced composite materials.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a 3D printing nozzle structure that realizes the supercooling of continuous fiber self-reinforced composite materials. It has the advantages of large product size and complex shape, short molding cycle, low cost and high production efficiency.

To achieve the above object, the present invention adopts the following technical solutions:

A 3D printing nozzle structure for realizing the supercooling of continuous fiber self-reinforced composite materials, comprising a liquefier 2, a nozzle 4 is connected to the lower end of the liquefier 2, a matrix phase 1 enters from the upper end of the liquefier 2, and is heated to a molten state through the liquefier 2 , into the nozzle 4, the temperature from the liquefier 2 to the nozzle 4 is lowered to below the melting point of the matrix phase 1 and not crystallized, forming a supercooled melt;

The side of the nozzle 4 is provided with fiber holes 5, through which the reinforcing phase 3 enters the supercooled melt of the matrix phase 1, and the reinforcing phase 3 wraps the matrix phase 1 and is extruded and cooled from the nozzle 4 to solidify and form.

The reinforcing phase 3 is continuous long fibers, the matrix phase 1 is resin, and the reinforcing phase 3 and the matrix phase 1 have the same chemical structure and different melting points; the cured and formed self-reinforced composite material is a thermoplastic polymer material with different physical forms.

The thermoplastic polymer material includes polyethylene (PE) base, polypropylene (PP) base, polylactic acid (PLA) base, nylon (PA) base, polymethyl methacrylate (PMMA) base, poly(terephthalic acid) Ethyl formate (PET) base, polybutylene terephthalate (PBT) base, polyethylene naphthalate (PEN), polyether ether ketone (PEEK), polyphenylene sulfide (PPS) base of polymer materials.

The distance L from the fiber hole 5 to the top of the nozzle 4 affects the temperature at which the reinforcement phase 3 is introduced into the matrix phase 1. Under the same printing temperature and cooling speed, the smaller L, the higher the temperature at which the reinforcement phase 3 is introduced into the matrix phase 1. Ensure that the temperature at the fiber hole 5 is not higher than the melting point of the reinforcing phase 3; the larger the L, the lower the temperature at which the reinforcing phase 3 is introduced into the matrix phase 1, to ensure that the reinforcing phase 3 wraps the matrix phase 1 and does not solidify before extruding the nozzle.

The diameter D of the fiber hole 5 is 0.8mm-1.5mm.

Utilize a method to realize the 3D printing nozzle structure of continuous fiber self-reinforced composite material supercooling, including the following steps:

1) Use computer-aided design software to establish a three-dimensional model of reinforced composite parts;

2) Determine the position of the fiber hole 5 according to the actual cooling rate during the 3D printing process;

3) Select the reinforcement phase 3 and the matrix phase 1 material. During the printing process, the reinforcement phase 3 is introduced from the fiber hole 5, immersed in the supercooled matrix phase 1, and extruded from the nozzle 4 to solidify and form;

4) Determine the printing temperature range.

Compared with the prior art, the beneficial effects of the present invention are as follows:

(1) Compared with the traditional technology of manufacturing self-reinforced composite materials, the present invention can quickly and efficiently manufacture self-reinforced composite material parts with specific and complex shapes without the need for molds, and utilizes the advantages of 3D printing to change the scanning distance, layer thickness, etc. to achieve mechanical Performance is controllable.

(2) The present invention utilizes the polymer supercooling degree to introduce the reinforcing phase 3 through the fiber hole 5 during the cooling process of 3D printing, which not only ensures that the introduced temperature is lower than the melting point of the reinforcing phase 3, does not cause thermal damage to the fibers, but also significantly increases the The processing temperature range of fiber self-reinforced composites solves the core problems and research difficulties of self-reinforced composites.

(3) The present invention controls the position of the fiber hole 5 to influence the temperature at which the reinforcement phase 3 is introduced into the matrix phase 1, thereby affecting the mechanical properties of the self-reinforced composite material; at the same time, the control of the cooling rate affects the crystallization temperature and crystallinity of the matrix phase 1 of the self-reinforced composite material ; The position of the fiber hole 5 and the cooling rate simultaneously affect the processing temperature window of the self-reinforced composite material.

Description of drawings

FIG. 1 is a schematic diagram of the structure of a 3D printing nozzle for realizing the supercooling of continuous fiber self-reinforced composite materials according to the present invention.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

Referring to FIG. 1, a 3D printing nozzle structure for realizing continuous fiber self-reinforced composite material undercooling includes a liquefier 2, a nozzle 4 is connected to the lower end of the liquefier 2, and a matrix phase 1 enters from the upper end of the liquefier 2, and passes through the liquefier 2. It is heated into a molten state, enters the nozzle 4, and is cooled to below the melting point of the matrix phase 1 and does not crystallize during the process from the liquefier 2 to the nozzle 4, forming a supercooled melt;

The side of the nozzle 4 is provided with fiber holes 5, through which the reinforcing phase 3 enters the supercooled melt of the matrix phase 1, and the reinforcing phase 3 wraps the matrix phase 1 and is extruded and cooled from the nozzle 4 to solidify and form.

The reinforcing phase 3 is continuous long fibers, the matrix phase 1 is resin, and the reinforcing phase 3 and the matrix phase 1 have the same chemical structure and different melting points; the cured and formed self-reinforced composite material is a thermoplastic polymer material with different physical forms.

The thermoplastic polymer material includes polyethylene (PE) base, polypropylene (PP) base, polylactic acid (PLA) base, nylon (PA) base, polymethyl methacrylate (PMMA) base, poly(terephthalic acid) Ethyl formate (PET) base, polybutylene terephthalate (PBT) base, polyethylene naphthalate (PEN), polyether ether ketone (PEEK), polyphenylene sulfide (PPS) base of polymer materials.

The distance L from the fiber hole 5 to the top of the nozzle 4 affects the temperature at which the reinforcing phase 3 is introduced into the matrix phase 1. Since the degree of supercooling of the thermoplastic polymer material is related to the cooling rate, the faster the cooling rate, the larger the temperature processing window. Under the same printing temperature and cooling speed, the smaller L is, the higher the temperature at which the reinforcement phase 3 is introduced into the matrix phase 1 is to ensure that the temperature at the fiber hole 5 is not higher than the melting point of the reinforcement phase 3; the larger the L is, the higher the reinforcement phase 3 is introduced into the matrix phase 1. The lower the temperature is, it should be ensured that the reinforcing phase 3 wraps the matrix phase 1 and does not solidify before extruding from the nozzle 4.

The diameter D of the fiber hole 5 is 0.8mm-1.5mm.

Utilize a method to realize the 3D printing nozzle structure of continuous fiber self-reinforced composite material supercooling, including the following steps:

1) According to the requirements of self-reinforced composite material parts, use SolidWorks of the computer-aided design software CAD to establish a 180×10×2 3D model of reinforced composite material parts, and export them as stl format files;

2) Determine the position of the fiber hole 5 according to the actual cooling rate in the 3D printing process. In this embodiment, the distance L from the fiber hole 5 to the top of the nozzle 4 is 5 mm, and the diameter D of the fiber hole 5 is 1 mm;

3) Select polyphenylene sulfide PPS fiber as the reinforcement phase 3, polyphenylene sulfide PPS resin as the matrix phase 1, the melting point of the PPS matrix is 282 degrees, the melting point of the reinforcement PPS fiber is 284 degrees, the printing temperature is set to 285 degrees, and the printing process The middle reinforcing phase 3 is introduced from the fiber hole 5, impregnated with the supercooled PPS matrix phase 1, and extruded and solidified from the nozzle 4;

4) Determine the printing temperature range: According to the cooling rate of the actual 3D printing process, it is measured that the initial crystallization temperature of the PPS matrix phase 1 is 192 degrees, and the temperature range of the reinforcement phase 3 introduced into the matrix phase 1 is between 192 degrees and 282 degrees, and the printing temperature increases. The higher the crystallization temperature of the matrix phase 1 is, the printing temperature can be raised to about 310 degrees. Therefore, in the printing temperature range of 282-310 degrees, the printing temperature is much higher than the melting point of the reinforcement phase 3, and the temperature at which the reinforcement phase 3 is introduced into the matrix phase 1 Much lower than the melting point of the matrix phase 1.

In the present invention, fiber holes 5 are punched in the nozzle 4 in the cooling process of the matrix phase 1 leaving the liquefier 2, and the reinforcing phase 3 is introduced into the molten matrix phase 1 at a temperature far lower than the melting point of the matrix phase 1; The processing temperature window is widened to several tens of degrees, and the high-fluidity matrix phase 1 is obtained without thermal damage caused by the reinforcement phase 3, which is conducive to the impregnation of the reinforcement phase 3 and the matrix phase 1; on the other hand, 3D printing is used to manufacture The advantage of the process is that it can quickly manufacture parts with specific complex shapes without molds; shorten the preparation cycle of the previous self-reinforced composite materials and reduce the cost; at the same time, it solves the interface problem between the 3D printing reinforcement phase 3 and the matrix phase 1. The invention comprehensively utilizes the interface of the self-reinforced composite material, the advantages of complete recyclability and the advantages of 3D printing, and realizes the rapid manufacture and green recycling of the fiber-reinforced composite material.

Claims (4)

1. The utility model provides a realize continuous fibers from 3D who strengthens combined material subcooling shaping and print shower nozzle structure, includes liquefier (2), its characterized in that: the lower end of the liquefier (2) is connected with a spray head (4), the matrix phase (1) enters from the upper end of the liquefier (2), is heated into a molten state by the liquefier (2), enters the spray head (4), and is cooled to a temperature below the melting point of the matrix phase (1) in the process from the liquefier (2) to the spray head (4) and is not crystallized to form a supercooled melt;

the side surface of the spray head (4) is provided with a fiber hole (5), the reinforced phase (3) enters the supercooled melt of the matrix phase (1) through the fiber hole (5), and the matrix phase (1) is wrapped by the reinforced phase (3) and is extruded out of the spray head (4), cooled and solidified and formed;

the reinforcing phase (3) is continuous long fiber, the matrix phase (1) is resin, the reinforcing phase (3) and the matrix phase (1) have the same chemical structure and have different melting points; the self-reinforced composite material formed by curing is a thermoplastic high polymer material with different physical forms;

the distance L between the fiber hole (5) and the top of the spray head (4) influences the temperature of the reinforcing phase (3) introduced into the matrix phase (1), and the smaller the L is, the higher the temperature of the reinforcing phase (3) introduced into the matrix phase (1) is, and the temperature at the fiber hole (5) is not higher than the melting point of the reinforcing phase (3) is ensured; the larger the L, the lower the temperature of the reinforcing phase (3) introduced into the matrix phase (1), and the reinforcing phase (3) is ensured not to be solidified before being wrapped by the matrix phase (1) and extruded out of the spray head.

2. The 3D printing nozzle structure according to claim 1, wherein: the thermoplastic polymer material comprises Polyethylene (PE) base, polypropylene (PP) base, polylactic acid (PLA) base, nylon (PA) base, polymethyl methacrylate (PMMA) base, polyethylene terephthalate (PET) base, polybutylene terephthalate (PBT) base, polyethylene naphthalate (PEN), polyether ether ketone (PEEK) and polyphenylene sulfide (PPS) base polymer materials.

3. The 3D printing nozzle structure according to claim 1, wherein: the diameter D of the fiber hole (5) is 0.8mm-1.5 mm.

4. The method of using the 3D print head structure for continuous fiber self-reinforced composite undercooling forming of claim 1, comprising the steps of:

1) establishing a three-dimensional model of the reinforced composite material part by using computer aided design software;

2) determining the position of the fiber hole (5) according to the actual cooling rate in the 3D printing process;

3) selecting materials of the reinforced phase (3) and the matrix phase (1), introducing the reinforced phase (3) from a fiber hole (5) in the printing process, impregnating the reinforced phase with the supercooled matrix phase (1), and extruding, solidifying and forming from a spray head (4);

4) a printing temperature interval is determined.

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