CN114474712A - Continuous fiber reinforced composite material efficient high-speed 3D printing head and using method thereof - Google Patents

Abstract

A high-efficiency high-speed 3D printing head of a continuous fiber reinforced composite material and a using method thereof are disclosed, the printing head comprises a plurality of single-nozzle modules for 3D printing of continuous fibers, the plurality of single-nozzle modules are arranged in a longitudinally staggered parallel array mode, horizontal center distance exists between every two adjacent single-nozzle modules in the X direction, vertical center distance exists between every two adjacent single-nozzle modules in the Y direction, and all the single-nozzle modules are fixed on a support; the using method comprises a single-nozzle module working mode and a multi-nozzle module cooperative working mode, and the feeding speed of the printed fiber prepreg yarns is increased through a low-temperature preheating high-speed wire feeding stage, so that the fiber friction damage is reduced; and connecting adjacent deposition lines together through a high-temperature hot-pressing flattening stage, and improving the forming speed and efficiency of the 3D printing composite material by combining a multi-nozzle module collaborative printing mode, so that the rapid manufacturing of the thermoplastic resin matrix composite material is realized.

Description

Continuous fiber reinforced composite material high-efficiency high-speed 3D printing head and its use method

technical field

The invention belongs to the technical field of additive manufacturing, and in particular relates to a continuous fiber reinforced composite material high-efficiency and high-speed 3D printing head and a method for using the same.

Background technique

The continuous fiber reinforced thermoplastic composite material 3D printing technology is mainly developed based on the material extrusion forming process in the traditional additive manufacturing technology. The main materials are fiber dry filaments and thermoplastic resin filaments as raw materials, which are heated, melted and extruded in the same print head and then stacked and formed layer by layer. The prepreg filament is then directly sent to the 3D printing nozzle to heat and melt to form layer by layer. At present, the fiber materials that have been used for 3D printing include carbon fiber, aramid fiber, glass fiber, etc., and the thermoplastic resin matrix includes PLA, PA, PC, PEEK, etc., and the tensile strength of the forming material exceeds 700MPa, far exceeding 3D The performance of printing pure materials has reached the level of traditional composite material manufacturing processes, and has formed typical application cases such as aircraft brackets, tooling fixtures, bicycle integrated frames, medical prostheses, etc., and has the conditions for industrial application.

However, there are still many problems and challenges to realize the 3D printing of continuous fiber reinforced thermoplastic composites from small batches and customized applications to batch and large-scale applications. The most obvious disadvantage is the low forming efficiency. The main reasons include the following two points :

1) The printing speed is low. The 3D printing speed of continuous fiber reinforced thermoplastic composites is much lower than the speed of 3D printing pure materials. Generally speaking, the printing speed of pure material extrusion molding process can reach more than 50mm/s (3000mm/min). The printing speed of in-situ dipping of silk is only about 100-200mm/min, and the printing speed of pre-preg silk has been improved, but the maximum can only reach about 20mm/s (1200mm/min). Continuous fiber 3D printing uses a lower forming speed. First, to increase the time of the material inside the nozzle, so that the thermoplastic resin can be completely melted and fully compounded with the fiber bundle, so as to reduce the internal pores of the composite material and improve the interface performance. In order to ensure the excellent performance of the composite material, due to the limited pressure inside the 3D printing nozzle, if the compounding time of the two is reduced, it will be more difficult to form a good microstructure; second, in order to prevent fiber damage, the fiber bundle is heated and melted through the nozzle. During the extrusion deposition process, there will be a shearing effect between the fiber bundle and the nozzle, and the shearing effect will be more serious at high moving speeds, while continuous fibers, especially carbon fibers, are relatively brittle and have poor shear resistance. Fiber damage or even fiber shearing is caused during the forming process, resulting in decreased mechanical properties or printing failure. For this reason, it is necessary to reduce the printing speed to ensure the forming quality.

2) The tow size is small. 3D printing of continuous fiber reinforced thermoplastic composite materials generally uses small tow fibers as raw materials. Taking carbon fiber as an example, 1K carbon fiber tow is more commonly used. The line width of this carbon fiber tow is relatively small during printing, generally about 1mm. And each time a single nozzle is used for forming, the forming characteristics of 3D printing line overlap and layer-by-layer accumulation lead to a sharp increase in the reciprocating motion path of the nozzle, while traditional composite material forming processes such as fiber laying technology often use 12K, 24K and other large sizes. Tow fiber ribbons are laid in parallel with multiple tows, and the line width of one forming is much higher than that of 3D printing. For 3D printing, large tow fibers can also be used in theory, but the problem brought by large tow fibers is that the feature size of the forming structure is limited, and it can often only be used to form some parts with relatively simple structures such as composite laminates , and cannot be used to form components with complex structures, especially those with small-scale features, which limit the application scenarios of 3D printing of continuous fiber-reinforced thermoplastic composites.

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 continuous fiber reinforced composite material high-efficiency high-speed 3D printing head and its using method, so as to realize the rapid manufacture of thermoplastic resin-based composite materials.

In order to achieve the above object, the present invention adopts the following technical solutions:

A continuous fiber reinforced composite material high-efficiency high-speed 3D printing head, comprising a plurality of single-nozzle modules 1 for continuous fiber 3D printing, the plurality of single-nozzle modules 1 are arranged in a longitudinally staggered parallel array, and adjacent single-nozzle modules in the X direction 1. There is a horizontal center distance 3, and there is a vertical center distance 4 between adjacent single nozzle modules 1 in the Y direction, and all single nozzle modules 1 are fixed on the bracket 2.

The single nozzle module 1 includes an active wire feeding unit 6, a preheating unit 7 and a hot pressing unit 8. An active wire feeding unit 6 is arranged above the preheating unit 7, and a hot pressing unit 8 is arranged behind the preheating unit 7. The active wire feeding unit 6 includes a wire feeding gear 9 and a fiber shearing mechanism 10 arranged below it; the preheating unit 7 includes a nozzle 13 and a heating block 12 connected to the upper part, and the heating block 12 is provided with a first heating unit 11 inside; The pressing unit 8 includes a hot pressing roller 15, a second heating unit 16 is arranged in the hot pressing roller 15, and the pressing unit 14 is connected to the hot pressing roller 15; Internally conveyed, the hot pressing roller 15 applies hot pressing to the deposited continuous fiber prepreg 5 .

The method for using a continuous fiber reinforced composite material efficient and high-speed 3D printing head includes:

In the working mode of the single nozzle module, the continuous fiber prepreg 5 is first fed into the preheating unit 7 through the wire feeding gear 9, and the preheating unit 7 controls the heating temperature under the action of the first heating unit 11 to vitrify the thermoplastic resin 20. The transition temperature, in the continuous fiber prepreg 5, the dry fiber 19 is wrapped by the thermoplastic resin 20, and the thermoplastic resin 20 is in direct contact with the surface of the nozzle 13 in a softened state; the continuous fiber prepreg 5 is 1K, 3K, etc. Tow fiber, the continuous fiber prepreg 5 is fed at a high printing speed (over 1500mm/min), and the continuous fiber is deposited according to a specific path. This process is the high-speed wire feeding stage 17; After the deposition is completed, the temperature of the hot pressing roller 15 is set above the melting point temperature of the thermoplastic resin 20, and the continuous fiber prepreg 5 is flattened and widened under the pressing force of the hot pressing roller 15 to obtain the actual scanning line width 21. The resin 20 is melted to connect the adjacent deposition lines together, and this process is the high temperature hot pressing flattening stage 18;

In the multi-nozzle module cooperative working mode, each single-nozzle module 1 performs tasks according to the process of the high-speed wire feeding stage 17 and the high-temperature hot-pressing flattening stage 18. The basic contour features 23 of the part include an equal-width straight line contour 24 and a widened straight line. The contour 25, the constant width curve contour 26, and the variable width curve contour 27 specifically include the following steps:

1) generating a continuous fiber filling path 22 according to the basic contour feature 23 and the geometric relationship of a single actual scanning line width 21;

2) According to the number of single nozzle modules 1, the generated continuous fiber filling paths 22 are allocated to different single nozzle modules 1. When the number of continuous fiber filling paths 22 is greater than the number of single nozzle modules, the strategy of multiple printing is adopted; When the number of filling paths 22 is less than the number of single nozzle modules 1, select the corresponding number of single nozzle modules 1, and finally obtain the motion paths that different single nozzle modules 1 need to execute;

3) According to the movement path assigned by each single nozzle module 1, design the execution action sequence of each single nozzle module 1, considering the vertical center distance 4 in the Y direction and the length of the movement path between different single nozzle modules 1, Determine the start printing time, fiber cutting time, and stop printing time of each single nozzle module 1, and form a multi-nozzle module coordinated work motion instruction;

4) Control the 3D printing head to complete the printing by using the multi-nozzle module cooperative work instruction.

During the cooperative operation of the multi-nozzle modules, there is an included angle 29 between the length direction of the bracket 2 and the printing direction 30. For the same printing direction 30, the rotating bracket 2 changes the size of the included angle 29. In the actual printing process, according to the basic outline of the part The different rotating brackets 2 of the feature 23 change the size of the included angle 29 in real time to realize variable line width printing and realize the forming of complex components.

The beneficial effects of the present invention are:

The invention increases the feeding speed of the printing fiber prepreg through the low-temperature preheating and high-speed wire feeding stage, and reduces the friction damage of the fiber; and then connects the adjacent deposition lines together through the high-temperature hot pressing and flattening stage, and at the same time combines the multi-nozzle modules to cooperate The printing method improves the forming speed and efficiency of 3D printing composite materials, and provides a feasible technical means for realizing batch and large-scale application of continuous fiber reinforced thermoplastic composite materials 3D printing.

Description of drawings

FIG. 1 is a schematic diagram of the overall structure of the 3D printing head of the present invention.

FIG. 2 is a schematic structural diagram of a single nozzle module of the present invention.

FIG. 3 is a schematic diagram of a high-speed printing method for a single nozzle module according to the present invention.

FIG. 4 is a schematic diagram of the multi-nozzle collaborative efficient printing method of the present invention.

FIG. 5 is a schematic diagram of the variable line width printing method of the present invention.

Detailed ways

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

Referring to Figure 1, a continuous fiber reinforced composite material high-efficiency high-speed 3D printing head includes a plurality of single nozzle modules 1 for continuous fiber 3D printing. Arranged in a parallel array, there is a horizontal center distance 3 between adjacent single nozzle modules 1 in the X direction, and a vertical center distance 4 between adjacent single nozzle modules 1 in the Y direction; because the line width of small tow fibers is relatively small when printing, If the single-extruder modules 1 are arranged in parallel horizontally, it is difficult to reduce the horizontal center distance 3 of the adjacent single-extruder modules 1 to the range of the fiber bundle printing line width due to the limitation of the physical space of the sprinklers, which will cause adjacent stacking lines. For this reason, a plurality of single nozzle modules 1 are arranged in a longitudinally dislocated parallel array; due to the dislocation distribution, the physical space limitation of the nozzles can be avoided at this time, and the center spacing of the adjacent nozzles in the X direction can be adjusted. Adjusted to within the range of the fiber bundle printing line width; all single nozzle modules 1 are fixed on the bracket 2.

Referring to FIG. 2 , the single nozzle module 1 includes an active wire feeding unit 6 , a preheating unit 7 and a hot pressing unit 8 . An active wire feeding unit 6 is provided above the preheating unit 7 , and an active wire feeding unit 6 is provided behind the preheating unit 7 . The hot pressing unit 8; the active wire feeding unit 6 includes a pair of wire feeding gears 9 and a fiber shearing mechanism 10 arranged below it; the preheating unit 7 includes a nozzle 13 and a heating block 12 whose upper part is threadedly connected, and the heating block 12 is internally provided. There is a first heating unit 11 for temperature control; the hot pressing unit 8 includes a hot pressing roller 15, a second heating unit 16 is arranged in the hot pressing roller 15, and the hot pressing roller 15 is connected with a pressing unit 14; the continuous fiber prepreg 5 The wire feed gear 9 is fed into the heating block 12 and the nozzle 13. The fiber cutting mechanism 10 between the wire feed gear 9 and the heating block 12 can cut the fiber continuous fiber prepreg 5. The first heating unit inside the heating block 12 11 is used for temperature control, and the hot pressing unit 8 is located behind the heating block 12, wherein the pressing unit 14 provides a downward pressing force, and the second heating unit 16 provides a heat source, both of which act together on the hot pressing roller 15, and the continuous process of the deposition is improved. The fiber prepreg 5 is heated and pressed.

The method for using a continuous fiber reinforced composite material efficient and high-speed 3D printing head includes:

Referring to FIG. 3 , in the working mode of the single nozzle module, the continuous fiber prepreg 5 is first fed into the preheating unit 7 under the action of the frictional force of the wire feeding gear 9 , and the preheating unit 7 will be heated under the action of the first heating unit 11 . The temperature is controlled near the glass transition temperature of the thermoplastic resin 20, so as to preheat the continuous fiber prepreg 5, so that the thermoplastic resin 20 is kept in a softened state without being completely melted, and has the ability to basically shape. In the prepreg 5, the dry fiber 19 is wrapped by the thermoplastic resin 20, and the thermoplastic resin 20 is in direct contact with the surface of the nozzle 13 in a softened state to lubricate and protect the dry fiber 19 and reduce fiber damage; the continuous fiber The prepreg 5 is 1K, 3K and other small tow fibers. The diameter of the filament is small, and the temperature can be heated to the glass transition temperature in a short time. Therefore, high printing speed (over 1500mm/min) can be used for feeding. Continuous fiber prepreg 5, and the deposition of continuous fibers is carried out according to a specific path. This process is a high-speed wire feeding stage 17. In the high-speed wire feeding stage 17, the continuous fiber prepreg 5 still maintains a small size and is not completely flattened , the deposition lines are still not combined to maintain a dispersed and independent state; after the continuous fiber prepreg 5 is deposited, the hot pressing unit 8 behind the preheating unit 7 applies hot pressing action to it, wherein the pressure unit 14 is a hot pressing roller 15 provides a downward pressing force, and the second heating unit 16 heats the hot pressing roller 15. Since the nozzle 13 is in a high-speed motion state, the temperature of the hot pressing roller 15 is set above the melting point temperature of the thermoplastic resin 20. 15 Under the action of the extrusion force, the continuous fiber prepreg 5 is flattened and widened to obtain the actual scanning line width 21, and the thermoplastic resin 20 is melted to connect the adjacent deposition lines together. This process is the high temperature hot pressing flattening stage 18.

Referring to FIG. 4 , in the cooperative working mode of the multiple nozzle modules, each single nozzle module 1 performs tasks according to the process of the high-speed wire feeding stage 17 and the high-temperature hot pressing and flattening stage 18, and the basic contour features 23 of common parts include equal-width straight lines. 24. The widened straight line profile 25, the equal-width curved profile 26, and the widened curved profile 27. The specific workflow includes the following steps:

1) generating a continuous fiber filling path 22 according to the basic contour feature 23 and the geometric relationship of a single actual scanning line width 21;

2) According to the number of single nozzle modules 1, the generated continuous fiber filling paths 22 are allocated to different single nozzle modules 1. When the number of continuous fiber filling paths 22 is greater than the number of single nozzle modules 1, the strategy of multiple printing is adopted, such as In Figure 4, the first printing 28-1, the second printing 28-2, and the third printing 28-3, when the number of continuous fiber filling paths 22 is less than the number of single nozzle modules 1, select the corresponding number of single nozzle modules 1 , as shown in the third print 28-3 in Figure 4, the motion paths required by different single nozzle modules 1 are finally obtained. In Figure 4, the motion paths corresponding to the single nozzle modules 1 include the first printing motion path 1 -1. The second printing motion path 1-2, the third printing motion path 1-3;

3) According to the movement path assigned by each single nozzle module 1, design the execution action sequence of each single nozzle module 1, considering the vertical center distance 4 in the Y direction and the length of the movement path between different single nozzle modules 1, Determine the start printing time, fiber cutting time, and stop printing time of each single nozzle module 1, and form a multi-nozzle module coordinated work motion instruction;

4) Control the 3D printing head to complete the printing by using the multi-nozzle module cooperative work instruction.

Referring to FIG. 5 , during the cooperative operation of the multi-nozzle modules, there is a certain angle 29 between the length direction of the bracket 2 and the printing direction 30 . For the same printing direction 30 , the rotating bracket 2 can change the size of the included angle 29 and change the included angle 29 The size of the horizontal center distance 3 in the printing direction 30 between individual nozzle modules can cause the change of the horizontal center distance 3 to cause the change of the continuous fiber scanning line width 21. The different rotating brackets 2 change the size of the included angle 29 in real time to realize variable line width printing and realize the forming of complex components.

Claims (4)

1. The utility model provides a high-efficient high-speed 3D of continuous fibers reinforcing combined material beats printer head which characterized in that: the device comprises a plurality of single-nozzle modules (1) for 3D printing of continuous fibers, wherein the plurality of single-nozzle modules (1) are arranged in a longitudinally staggered parallel array mode, a horizontal center distance (3) exists between every two adjacent single-nozzle modules (1) in the X direction, a vertical center distance (4) exists between every two adjacent single-nozzle modules (1) in the Y direction, and all the single-nozzle modules (1) are fixed on a support (2).

2. The continuous fiber reinforced composite high efficiency high speed 3D printhead of claim 1, wherein: the single-nozzle module (1) comprises a driving wire feeding unit (6), a preheating unit (7) and a hot-pressing unit (8), wherein the driving wire feeding unit (6) is arranged above the preheating unit (7), and the hot-pressing unit (8) is arranged behind the preheating unit (7); the active wire feeding unit (6) comprises a wire feeding gear (9) and a fiber shearing mechanism (10) arranged below the wire feeding gear; the preheating unit (7) comprises a nozzle (13) and a heating block (12) connected with the upper part of the nozzle, and a first heating unit (11) is arranged in the heating block (12); the hot pressing unit (8) comprises a hot pressing roller (15), a second heating unit (16) is arranged in the hot pressing roller (15), and the hot pressing roller (15) is connected with a pressure unit (14); the continuous fiber pre-impregnated filaments (5) are conveyed to the interior of the heating block (12) and the nozzle (13) through the wire feeding gear (9), and the hot pressing roller (15) applies hot pressing action to the deposited continuous fiber pre-impregnated filaments (5).

3. The method for using the continuous fiber reinforced composite high-efficiency high-speed 3D printing head as claimed in claim 2, wherein the method comprises the following steps:

in the working mode of a single spray head module, continuous fiber pre-impregnated filaments (5) are firstly sent into a preheating unit (7) through a wire feeding gear (9), the preheating unit (7) controls the heating temperature to be the glass transition temperature of thermoplastic resin (20) under the action of a first heating unit (11), dry fiber filaments (19) in the continuous fiber pre-impregnated filaments (5) are wrapped by the thermoplastic resin (20), and the thermoplastic resin (20) is directly contacted with the surface of a spray head in a softened state; the continuous fiber prepreg silk (5) is 1K or 3K small tow fiber, the continuous fiber prepreg silk (5) is fed at a high printing speed exceeding 1500mm/min, and deposition of the continuous fiber is carried out according to a specific path, wherein the process is a high-speed silk feeding stage (17); after the deposition of the continuous fiber pre-impregnated filaments (5) is finished, the temperature of a heating roller (15) is set to be higher than the melting point temperature of thermoplastic resin (20), the continuous fiber pre-impregnated filaments (5) are flattened and widened under the hot pressing action of the heating roller (15), the actual scanning line width (21) is obtained, meanwhile, the thermoplastic resin (20) is melted to connect adjacent deposition lines together, and the process is a high-temperature hot pressing flattening stage (18);

under the cooperative working mode of the multiple spray head modules, each single spray head module (1) executes tasks according to the flow of a high-speed wire feeding stage (17) and a high-temperature hot-pressing flattening stage (18), and the basic contour characteristics (23) of the part comprise an equal-width straight line contour (24), a widening straight line contour (25), an equal-width curve contour (26) and a widening curve contour (27), and specifically comprise the following steps:

1) generating a continuous fiber fill path (22) from the geometric relationship of the base profile features (23) and the single actual scan line width (21);

2) according to the number of the single-nozzle modules (1), distributing the generated continuous fiber filling paths (22) to different single-nozzle modules (1), and when the number of the continuous fiber filling paths (22) is larger than the number of the single-nozzle modules, adopting a multi-printing strategy; when the number of the continuous fiber filling paths (22) is smaller than that of the single-nozzle modules (1), selecting the corresponding number of the single-nozzle modules (1), and finally obtaining the motion paths required to be executed by different single-nozzle modules (1);

3) according to the motion path distributed by each single-nozzle module (1), designing the execution action time sequence of each single-nozzle module (1), and considering the vertical center distance (4) in the Y direction between different single-nozzle modules (1) and the length of the motion path, determining the printing starting time, the fiber shearing time and the printing stopping time of each single-nozzle module (1) to form a multi-nozzle module cooperative work motion instruction;

4) and controlling the 3D printing head to complete printing by utilizing the cooperative working instruction of the multiple spray head modules.

4. The method of claim 3, wherein: in the process of cooperative work of the multiple spray head modules, an included angle (29) exists between the length direction of the support (2) and the printing direction (30), for the same printing direction (30), the size of the included angle (29) is changed by the rotating support (2), in the actual printing process, the size of the included angle (29) is changed in real time according to different rotating supports (2) of basic contour characteristics (23) of parts, line width changing printing is achieved, and forming of complex components is achieved.

Images