High efficiency additive manufacturing apparatus and molding method for thermoplastic composites

Abstract

The application discloses a kind of thermoplastic composite high-efficiency additive manufacturing device and forming method, preheating method includes first preheating stage: resin matrix is preheated to 10-30 ℃ below resin matrix glass transition temperature;Second preheating stage: resin matrix is preheated to higher than resin matrix glass transition temperature and lower than the melting point temperature of resin matrix;Third preheating stage: resin matrix is preheated to 20-50 ℃ higher than the melting point temperature of resin matrix.First preheating stage, can dry the moisture on the surface of printing filament;Second preheating stage, improve fluidity;Third preheating stage, promote resin matrix melting, reach flowing state, carry out sufficient infiltration to fiber, with good plasticity simultaneously, improve the print feasibility, for FDM laying forming process, it can improve the interlaminar adhesion of printed part, reduce porosity, to improve the comprehensive mechanical properties of printed product in turn.In addition, since the fluidity of resin matrix increases, printing speed can also be improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of continuous fiber 3D printing, and particularly relates to a thermoplastic composite material efficient additive manufacturing device and a forming method. BACKGROUND

[0002] 3D printing is a main form of realizing "additive manufacturing", and is regarded as an important content of advanced manufacturing in many countries in the world. Carbon fiber composite materials have great advantages in fields with strict requirements on density, weight and fatigue characteristics and occasions with high temperature and high chemical stability requirements. Traditional continuous carbon fiber forming manufacturing includes a series of processes such as weaving, gluing, cloth laying and pressing, and has high precision requirements and loss of a mold, and is limited by model complexity to some extent, which restricts the full play of the role of carbon fiber materials. 3D printing has the characteristics of one-piece forming and no limitation of complexity, and is used for forming and manufacturing of continuous carbon fiber composite materials, can play the advantages of light weight and high strength of materials and one-piece forming of 3D printing, and has broad application prospects for manufacturing carbon fiber parts with complex structure and shape.

[0003] In the existing fiber continuous 3D printing process, the resin matrix is often preheated first, and for products with low fiber content, the resin matrix is not preheated enough, resulting in poor interlayer bonding force and poor mechanical properties. SUMMARY

[0004] The purpose of the present application is to provide a thermoplastic composite material efficient additive manufacturing device and a forming method, to improve the preheating effect of the resin matrix, improve the interlayer bonding force of the printed product, and improve the comprehensive mechanical properties of the printed product.

[0005] The purpose of the present application is achieved by a thermoplastic composite material efficient additive forming method, comprising

[0006] The first preheating stage is to preheat the resin matrix to 10-30 DEG C lower than the glass transition temperature of the resin matrix;

[0007] The second preheating stage is to preheat the resin matrix to higher than the glass transition temperature of the resin matrix and lower than the melting point temperature of the resin matrix;

[0008] The third preheating stage is to preheat the resin matrix to 20-50 DEG C higher than the melting point temperature of the resin matrix.

[0009] Further, the resin matrix is one of nylon, ABS resin, polylactic acid, polyamide, polyphenylene sulfide, polyether ether ketone resin, and the fiber is one or more of continuous carbon fiber, continuous aramid fiber, continuous ceramic fiber, continuous glass fiber and continuous silicon carbide fiber.

[0010] Thermoplastic composite material high-efficiency additive manufacturing device, comprising first preheating block, second preheating block and third preheating block arranged in sequence, heat insulation layer is arranged between first preheating block and second preheating block and between second preheating block and third preheating block, and the center of first preheating block, second preheating block, third preheating block and heat insulation layer is provided with feeding through hole.

[0011] Further, the feeding through hole of the first preheating block, the second preheating block and the third preheating block is circular truncated cone, and in the feeding direction, the diameter of the feeding through hole gradually decreases.

[0012] Further, it also includes a heating module, the heating module has a heating cavity inside, one end of the heating cavity is connected with the feeding through hole, the other end is connected with a nozzle print head, the nozzle print head is provided with a discharging channel.

[0013] Further, the heating cavity is provided with a guide column, the guide column has a guide through hole, the guide through hole includes a spiral segment and a straight segment, the side wall of the spiral segment is provided with a spiral guide groove, and the diameter of the spiral segment is greater than the diameter of the straight segment, the spiral segment is connected with the feeding through hole, the straight segment is connected with the discharging channel of the nozzle print head, and the diameter of the discharging channel is smaller than the diameter of the straight segment.

[0014] Further, the outer wall of the guide column is connected with the inner wall of the heating module through threads.

[0015] Further, the heating module and the third preheating block are also provided with a heat insulation layer.

[0016] The beneficial effects of the present application are: the first preheating stage can dry the moisture on the surface of the printing filament; the second preheating stage makes the resin matrix fully glass transition, improving the fluidity; the third preheating stage promotes the resin matrix to melt and reach the flow state, fully infiltrates the fiber, and has good plasticity, improves the printing feasibility, for FDM laying forming process, can improve the interlayer bonding strength of the printed part, reduce the porosity, and further improve the comprehensive mechanical properties of the printed product. In addition, due to the increased fluidity of the resin matrix, the printing speed can also be improved. The resin matrix is preheated in three stages, which improves the uniformity of the resin matrix preheating and prevents the situation that the temperature of the part in contact with the preheating device is high, while the temperature of the resin matrix at the center is too low. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a schematic diagram of the preheating device of the present application.

[0018] Figure 2 It is a schematic diagram of the printing device of the present application.

[0019] Figure 3This is a schematic diagram of the nozzle printhead ejection outlet. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] The present invention provides a high-efficiency additive manufacturing method for thermoplastic composite materials, comprising:

[0022] First preheating stage: Preheat the resin matrix to 10-30℃ below its glass transition temperature. Because fibers have a strong adsorption capacity and easily absorb moisture from the air, which can affect the quality of the product, this stage is mainly used to dry the moisture on the fiber surface. The preheating temperature should not be too high, generally set between 50-120℃. The specific temperature depends on the resin matrix used, and is generally 10-30℃ below the glass transition temperature of the resin matrix so that the evaporated moisture can be discharged from the inlet.

[0023] The second preheating stage involves preheating the resin matrix to a temperature above its glass transition temperature but below its melting point. This stage allows the resin matrix to undergo a full glass transition, softening it and improving its fluidity. Simultaneously, the resin matrix becomes more tightly bound, reducing pore size and forcing air out through a counter-current flow, thereby lowering the product's porosity.

[0024] The third preheating stage involves preheating the resin matrix to a temperature 20-50°C above its melting point. This stage melts the resin matrix, transforming it from a solid to a liquid state, further increasing its fluidity. The liquid resin matrix allows for thorough impregnation of continuous fibers, while also increasing plasticity and improving printing feasibility. For FDM layup processes, this improves interlayer adhesion, reduces porosity, and ultimately enhances the overall mechanical properties of the printed product. Furthermore, the increased resin matrix fluidity allows for increased feed rate, thus improving printing speed.

[0025] Preheating the resin matrix in three stages can improve the uniformity of preheating and prevent the external parts in contact with the preheating device from having a high temperature while the temperature of the resin matrix in the center is too low.

[0026] After preheating, 3D printing can begin.

[0027] The resin matrix of the present invention may be one of nylon, ABS resin, polylactic acid, polyamide, polyphenylene sulfide, and polyether ether ketone resin, while the fiber may be one or more of continuous carbon fiber, continuous aramid fiber, continuous ceramic fiber, continuous glass fiber, and continuous silicon carbide fiber.

[0028] The preheating device of the present invention, such as Figure 1As shown, it includes a first preheating block 1, a second preheating block 3 and a third preheating block 4 arranged in sequence. A heat insulation layer 2 is provided between the first preheating block 1 and the second preheating block 3 and between the second preheating block 3 and the third preheating block 4. A feed through hole is provided in the center of the first preheating block 1, the second preheating block 3, the third preheating block 4 and the heat insulation layer 2.

[0029] The first preheating block 1, the second preheating block 3, and the third preheating block 4 all have heating functions for heating the resin matrix. The first preheating block 1, the second preheating block 3, and the third preheating block 4 correspond to the first preheating stage, the second preheating stage, and the third preheating stage, respectively. The preheating temperature of the first preheating block 1 is 10-30°C lower than the glass transition temperature of the resin matrix. The preheating temperature of the second preheating stage is higher than the glass transition temperature of the resin matrix but lower than the melting point temperature of the resin matrix. The preheating temperature of the third preheating stage is 20-50°C higher than the melting point temperature of the resin matrix.

[0030] The insulation layer 2 serves as an insulation layer and can be made of insulation cotton. This allows the first preheating block 1, the second preheating block 3, and the third preheating block 4 to be independent preheating blocks that do not affect each other, thereby accurately controlling the preheating temperature of the three stages.

[0031] The feed through-holes are used for the resin matrix and fibers to pass through. The feed through-holes on the first preheating block 1, the second preheating block 3, the third preheating block 4, and each heat insulation layer 2 are coaxially arranged. The feed through-holes of the first preheating block 1, the second preheating block 3, and the third preheating block 4 are all frustum-shaped, and the diameter of the feed through-holes gradually decreases in the feeding direction to facilitate the guidance and positioning of the printing filament.

[0032] The manufacturing apparatus of the present invention, such as Figure 2 As shown, including as Figure 1 The preheating device and heating module 6 shown have a heating chamber inside. One end of the heating chamber is connected to the feed through hole, and the other end is connected to the nozzle print head 7. The nozzle print head 7 has a discharge channel inside.

[0033] The heating module 6 is used to heat the resin matrix to the printing temperature required by the 3D printing process. The nozzle print head 7 is used to eject the resin matrix and continuous fibers. During the printing process, the nozzle print head 7 moves according to the set trajectory to print the product.

[0034] The discharge channel is a long, narrow, straight hole with smooth sidewalls, providing good heat insulation and reducing flow resistance. During the printing process, if fibers accumulate in the discharge channel, they can be pushed out under the printing pressure, thus acting as a self-cleaning discharge channel.

[0035] The nozzle printhead 7 is made entirely of high-manganese alloy steel, which has good wear resistance. The ends are rounded, creating a flared, funnel-shaped outlet for the material discharge channel. Figure 3 As shown, the main purpose is to reduce stress concentration and avoid damaging the fully plasticized prepreg yarn.

[0036] Furthermore, a guide post 5 is provided inside the heating chamber. The guide post 5 has a guide through hole, which includes a spiral section and a straight section. The side wall of the spiral section is provided with a spiral guide groove, and the diameter of the spiral section is larger than the diameter of the straight section. The spiral section is connected to the feed through hole, and the straight section is connected to the discharge channel of the nozzle print head 7. The diameter of the discharge channel is smaller than the diameter of the straight section.

[0037] The guide post 5 is made of a material with high thermal conductivity to facilitate the rapid transfer of heat generated by the heating module 6 to the resin matrix. The spiral guide grooves on the inner wall of the spiral section increase the contact area between the resin matrix and the guide post 5, improving heating efficiency. Simultaneously, the vertical matrix can move spirally along the guide grooves, improving heating uniformity, extending the flow path, and ensuring optimal heating performance. The continuous fiber is located at the center of the guide through-hole.

[0038] The outer wall of the guide post 5 is connected to the inner wall of the heating module 6 by threads, and the outer wall of one end of the nozzle printhead 7 is connected to the inner wall of the guide post 5 by threads. Most of the nozzle printhead 7 is located inside the heating chamber of the heating module 6, with only the nozzle at the end protruding from the heating module 6. This helps to keep the nozzle printhead 7 warm, prevents it from breaking due to excessively low temperature, and effectively improves the quality of the printed products.

[0039] A heat insulation layer 2 is also provided between the heating module 6 and the third preheating block 4. The heat insulation layer 2 serves to block heat and prevent the heat from the heating module 6 from being transferred to the third preheating block 4 and affecting the preheating temperature.

[0040] To reduce heat loss, an insulation layer can be installed on the outside of the heating module 6, the first preheating block 1, the second preheating block 3, and the third preheating block 4.

[0041] The printing method of the present invention employs, as follows: Figure 2 The printing device shown extrudes resin matrix prepreg filaments into the feed port of the preheating device. The first preheating block 1 preheats the resin matrix to 10-30°C below the glass transition temperature of the resin matrix. The second preheating block 3 preheats the resin matrix to a temperature above the glass transition temperature of the resin matrix but below the melting point temperature of the resin matrix. The third preheating block 4 preheats the resin matrix to a temperature 20-50°C above the melting point temperature of the resin matrix. Then the resin matrix enters the heating module 6, is heated to the printing temperature by the heating module 6, and is ejected from the nozzle printhead 7 for layer-by-layer printing.

[0042] Example 1

[0043] The resin matrix is ​​made of PPS, and the fiber is made of continuous carbon fiber.

[0044] The glass transition temperature of PPS is approximately 106℃, and its melting point is approximately 284℃. Therefore, the preheating temperature for the first preheating stage is 90-100℃, the preheating temperature for the second preheating stage is 200-250℃, and the preheating temperature for the third preheating stage is 300-320℃. Figure 2 The printing device shown is used for printing.

[0045] For carbon fiber printing filaments, due to the good heat dissipation properties of carbon fiber itself, heat preservation is required during the printing process. Conventional continuous carbon fiber printing speeds are relatively slow, ranging from 100-300 mm / min, with interlayer adhesion of the printed product around 20 MPa, flexural strength between 400-500 MPa, and flexural modulus between 30-40 GPa. In contrast, this invention achieves a printing speed of 500-600 mm / min. By improving the preheating process of the resin matrix, printing efficiency can be increased, and the interlayer adhesion of the printed product is improved to around 40 MPa. Furthermore, the flexural strength and modulus reach approximately 800 MPa and 60 GPa respectively, significantly enhancing the mechanical properties.

[0046] The overall printing process for other types of resin-based prepreg filaments is similar, but appropriate preheating temperatures need to be set for different resin matrices.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-efficiency additive manufacturing apparatus for thermoplastic composite materials, characterized in that, It includes a first preheating block (1), a second preheating block (3) and a third preheating block (4) arranged in sequence. A heat insulation layer (2) is provided between the first preheating block (1) and the second preheating block (3) and between the second preheating block (3) and the third preheating block (4). A feed through hole is provided in the center of the first preheating block (1), the second preheating block (3), the third preheating block (4) and the heat insulation layer (2). The feed through holes of the first preheating block (1), the second preheating block (3) and the third preheating block (4) are all frustum-shaped, and the diameter of the feed through holes gradually decreases in the feeding direction; It also includes a heating module (6), which has a heating chamber inside. One end of the heating chamber is connected to the feed through hole, and the other end is connected to a nozzle print head (7). The nozzle print head (7) is provided with a discharge channel. The heating chamber is provided with a guide post (5), which has a guide through hole. The guide through hole includes a spiral section and a straight section. The side wall of the spiral section is provided with a spiral guide groove, and the diameter of the spiral section is larger than the diameter of the straight section. The spiral section is connected to the feed through hole, and the straight section is connected to the discharge channel of the nozzle print head (7). The diameter of the discharge channel is smaller than the diameter of the straight section.

2. The high-efficiency additive manufacturing apparatus for thermoplastic composite materials as described in claim 1, characterized in that, The outer wall of the guide post (5) is connected to the inner wall of the heating module (6) by threads.

3. The high-efficiency additive manufacturing apparatus for thermoplastic composite materials as described in claim 1, characterized in that, A heat insulation layer (2) is also provided between the heating module (6) and the third preheating block (4).

4. A high-efficiency additive manufacturing method for thermoplastic composite materials, characterized in that, The high-efficiency additive manufacturing apparatus for thermoplastic composite materials as described in any one of claims 1 to 3 is employed. It also includes the following steps: First preheating stage: Preheat the resin matrix to 10-30℃ below the glass transition temperature of the resin matrix; Second preheating stage: Preheat the resin matrix to a temperature higher than the glass transition temperature of the resin matrix but lower than the melting point temperature of the resin matrix; The third preheating stage: preheat the resin matrix to a temperature 20-50°C above the melting point of the resin matrix.

5. The efficient additive manufacturing method for thermoplastic composite materials as described in claim 4, characterized in that, The resin matrix is ​​one of nylon, ABS resin, polylactic acid, polyamide, polyphenylene sulfide, and polyetheretherketone resin, and the fiber is one or more of continuous carbon fiber, continuous aramid fiber, continuous ceramic fiber, continuous glass fiber, and continuous silicon carbide fiber.

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