CN114834034A - In-situ electronic control additive manufacturing device and process for functional composite material - Google Patents

Abstract

The invention discloses an in-situ electronic control additive manufacturing device and a process for a functional composite material, wherein a printing nozzle with a nested structure is used, a plate-type metal mesh frame is arranged at the printing nozzle, an external high-voltage electrostatic generator is connected with the plate-type metal mesh frame and a printing substrate, a high-voltage electrostatic field and functional reinforcing materials such as fibers and the like generate interaction to control the orientation of the functional reinforcing materials such as the fibers and the like, the functional reinforcing materials such as the fibers and the like are conveyed to the surface of a printing substrate layer through the nozzle while printing layer by layer, the direction controllable distribution manufacturing of the functional reinforcing materials such as the fibers, carbon nanotubes, carbon fibers, graphene and the like in a 3D printing composite material is realized under the control of an external electric field, the technical essential defect of weak combination between 3D printing layers is overcome, and the oriented manufacturing of the 3D printing structure function of the composite material can be realized.

Description

A device and process for in-situ electronically controlled additive manufacturing of functional composite materials

technical field

The invention relates to the technical field of 3D printing of composite materials, in particular to a device and a process for in-situ electronically controlled additive manufacturing of functional composite materials.

Background technique

3D printing of material extrusion molding can realize the integrated molding of fiber-reinforced composite materials. Due to the addition of functional reinforcing materials such as fibers (such as carbon fiber, graphene, etc.) to the matrix material, it has mechanical properties and functional characteristics compared with traditional polymer 3D printing. (such as electromagnetic shielding). However, because reinforcing materials such as fibers, carbon nanotubes and other functional fillers are physically mixed in the matrix material, and are made into filaments suitable for printing processes through screws, or are directly printed and formed through screw extrusion, fibers, carbon nanotubes, etc. The distribution and direction of functional reinforcing materials such as tubes, carbon fibers, and graphene in the printing filament cannot be controlled during the printing process, resulting in very limited improvement in the interlayer performance of the printed samples by functional reinforcing materials such as fibers, resulting in composite 3D printing technology. The huge anisotropy in the Z direction and other directions is one of the technical difficulties that limit the application of composite 3D printing technology in the engineering field, and it is impossible to realize the controllable distribution of functional materials in the overall component manufacturing.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an in-situ electronically controlled additive manufacturing device and process for functional composite materials, so as to overcome the defects of the prior art. Large increase, improve the mechanical properties of the part, realize the controllability of the orientation, gradient and position of the functional enhancement material, and improve the functional characteristics of the part.

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

An in-situ electronically controlled additive manufacturing device for functional composite materials, comprising one or more sets of nested nozzles, a printing substrate is arranged below the nested nozzles, and the nested nozzles include a matrix material for printing a matrix material Nozzle, the outer side of the base material nozzle is sleeved with an enhanced interlayer strength nozzle for implanting the functional enhancement material into the base material, the outer side of the outlet of the base material nozzle is sleeved with a plate-shaped metal mesh frame, and the plate-shaped metal mesh The frame is located at the outlet of the nozzle for enhancing the strength between layers. The plate-shaped metal mesh frame is connected to the high-voltage electrostatic generator through wires, and the cooperation of the high-voltage electrostatic generator and the plate-shaped metal mesh frame can realize the implantation of the functional enhancement material into the matrix material. Direction and position, the high-voltage electrostatic generator and the printing substrate are both grounded.

Further, the resistivity of the functional enhancement material is less than 10 ⁷ Ω·cm in a standard state.

Further, the functional reinforcing material adopts conductive short fibers.

Further, the short conductive fibers are metal-based conductive fibers, polymer-based conductive fibers, carbon-based conductive fibers or composite conductive fibers.

Further, the high-voltage electrostatic generator is equipped with a control box for controlling voltage variation, and the voltage is used to determine the position and direction of the functional enhancement material, thereby achieving different enhancement effects.

Further, the voltage value of the high-voltage electrostatic generator is 40-60kV.

An in-situ electronically controlled additive manufacturing process for functional composite materials. While the substrate material is printed by the nozzle, the functional enhancement material is charged in contact with the charged plate-shaped metal mesh frame at the outlet of the nozzle that enhances the interlayer strength. Polarization occurs in the mesh, and the charges with the same polarity as the metal mesh frame are concentrated at the end far away from the metal mesh frame, while the opposite charges are concentrated at the end close to the metal mesh frame. When the frame is in contact, a conductive current is generated in the functional enhancement material, and the functional enhancement material generates charges. By controlling the applied field strength, the size and dielectric constant of the functional enhancement material, the functional enhancement material translates, rotates and has a period under the action of electrostatic force. It vibrates and implants into the molten matrix material in a certain orientation, and the molten matrix material solidifies to fix the functional enhancement material in it. When the next layer of printing is performed, the next layer of molten matrix material will completely the functional enhancement material. Covering and curing to realize the connection between layers. During the printing process, the distance between the nested nozzle and the printing substrate remains unchanged, and the substrate material and the functional enhancement material are coaxially output and printed until the printed part is completed.

Further, the functional reinforcing material adopts conductive short fibers, and the conductive short fibers are subjected to fiber opening treatment before use.

Further, the high-voltage electrostatic generator is equipped with a control box for controlling the voltage change, and the size of the electric field is controlled by the control box to control the orientation and content of the functional enhancement material. gradient.

Compared with the prior art, the present invention has the following beneficial technical effects:

1) The present invention uses the interaction between the high-voltage electrostatic field and the fiber to control the orientation of the functional reinforcing material, so that it is implanted into the molten matrix material in a certain orientation, and the connection between the two layers of matrix materials is realized, so as to realize the interlayer of the 3D printing part. The enhancement of strength can achieve a large increase in the interlayer strength without destroying the original structure, improve the mechanical properties of the part, realize the controllability of fiber orientation, gradient and position, and improve the functional characteristics of the part. 2) The functional reinforcing material vertically implanted into the molten matrix material of the present invention can enhance the interlayer strength to the greatest extent, and different fibers are printed with different orientations and densities in different parts to achieve different functional properties. 3) The present invention can retain the integrity of the original structural design and the controllability of the functional design to the greatest extent. 4) The substrate material nozzle and the interlayer strength-enhancing nozzle of the present invention print in parallel, which saves time and has a simple process.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

Figure 1 is a schematic structural diagram of an in-situ electronically controlled additive manufacturing device for functional composite materials;

Figure 2 is a schematic structural diagram of controlling different contents of functional enhancing materials;

FIG. 3 is a schematic structural diagram of controlling different orientations of functional enhancing materials;

Figure 4 is a schematic diagram of the structure of controlling different functional enhancement materials.

Among them, 1. Base material nozzle; 2. Base material; 3. Printing substrate; 4. Grounding; 5. High voltage electrostatic generator; 6. Plate metal mesh frame; 7. Functional enhancement material; .

Detailed ways

In order to make those skilled in the art better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only Embodiments are part of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that the terms "first", "second" and the like in the description and claims of the present invention and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific sequence or sequence. It is to be understood that the data so used may be interchanged under appropriate circumstances such that the embodiments of the invention described herein can be practiced in sequences other than those illustrated or described herein. Furthermore, the terms "comprising" and "having" and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those expressly listed Rather, those steps or units may include other steps or units not expressly listed or inherent to these processes, methods, products or devices.

The present invention designs a nozzle with a nested structure to realize the coaxial output printing of the base material and the functional enhancement material. A plate-type metal mesh frame 6 is installed at the printing nozzle, and the plate-type metal mesh is connected through an external high-voltage electrostatic generator 5 Frame 6 interacts with the printing substrate 3, and the high-voltage electrostatic field interacts with the functional enhancement material to control the orientation of the functional enhancement material. While printing layer by layer, the functional enhancement material is transported to the surface of the printing substrate layer through the nozzle, that is, the upper and lower layers. interlayer, so as to play the role of interlayer reinforcement. At the same time, through the intermittent voltage control and the change of the size and dielectric constant of the functional enhancement material, different densities of different functional enhancement materials can be printed on different parts of the part, and the magnitude of the applied voltage is controlled. , to realize the printing of functional enhancement materials in different orientations of different parts, so as to achieve controlled manufacturing.

Example

The 3D printing device of this embodiment includes at least one set of nested nozzles, the inside is the substrate material nozzle 1, the outside is the enhanced interlayer strength nozzle 8, and a plate-shaped metal mesh frame 6 is installed at the outlet of the enhanced interlayer strength nozzle 8. The metal mesh frame 6 is connected to one end of the high-voltage electrostatic generator 5 through a wire, and the printing substrate 3 is grounded. In this embodiment, the functional enhancement material adopts conductive short fibers. The specific method for enhancing the interlayer strength is as follows: while the substrate material nozzle 1 is printing, the conductive short fibers are in contact with the charged plate-type metal mesh frame 6 at the outlet of the enhanced interlayer strength nozzle 8 to be charged, and the conductive short fibers are charged at the same time. Polarization occurs in the electric field, and the electric charges with the same polarity as the flat metal mesh frame 6 are concentrated at the end far away from the flat metal mesh frame 6, while the opposite charges are concentrated at the end close to the flat metal mesh frame 6. When the flat metal mesh frame 6 is in contact, since the electrical conductivity of the flat metal mesh frame 6 is higher than that of the conductive short fibers 7, a certain conductive current is generated in the conductive short fibers, and the conductive short fibers generate charges, so that the conductive short fibers are in the electric field. It has great straightness and flying ability. By controlling the external field strength, the size and dielectric constant of the conductive short fibers, the conductive short fibers translate, rotate and periodically vibrate under the action of electrostatic force, and are planted in a certain orientation. into the matrix in the molten state near the matrix material 2, and the molten matrix solidifies to fix the conductive short fibers 7 in the matrix. When printing the next layer, the next layer of molten matrix completely covers and solidifies the conductive short fibers 7. , to realize the connection between layers. During the printing process, the distance between the printing nozzle and the printing substrate 3 remains unchanged, and the substrate material 2 and the conductive short fibers are coaxially output for printing. As the layer height increases, the enhancement effect is not change until the printed part is completed, as shown in Figure 1.

m为导电短纤维自身的重量，F_q为导电短纤维在静电场中所受的电场力，G为导电短纤维自身重力，F_R为导电短纤维在静电场中运动时所受的空气阻力，v为导电短纤维的运动速度，与外加场强、导电短纤维本身因素如导电短纤维的种类、长短、粗细、空气阻力系数有关，导电短纤维的动量P＝mv反映了导电短纤维的植入深度。导电短纤维在电场中还围绕固定轴转动，定向过程的方程为：Iθ″+M_R(θ′)+M_P(θ)+M_q(θ)＝0，I为导电短纤维的惯性矩，θ″为角加速度，θ′为角速度，θ为导电短纤维刚进入电场时长半轴方向与外电场E₀间的夹角，M_R(θ′)为介质的阻尼力矩，M_P(θ)为极化电荷产生的转动力矩，M_q(θ)为感应电荷产生的转动力矩，定向过程方程与导电短纤维本身因素、外加场强和空气阻力系数有关。The principle of the present invention: the present invention realizes the control of the direction and position of the conductive short fibers through the interaction between the high-voltage electrostatic field and the conductive short fibers. The fibers have the greatest increase in the interlayer strength, the position of the fibers determines the bonding between the layers, and different conductive short fibers are implanted in different positions, resulting in different functional properties. Assuming that the conductive short fibers are slender ellipsoids, the theoretical equation for the translation of a single conductive short fiber in a high-voltage electrostatic field is:

m is the weight of the conductive short fiber itself, F _q is the electric field force of the conductive short fiber in the electrostatic field, G is the self-gravity of the conductive short fiber, and F _R is the air resistance of the conductive short fiber when it moves in the electrostatic field , v is the moving speed of the conductive short fibers, which is related to the applied field strength, the conductive short fibers themselves, such as the type, length, thickness, and air resistance coefficient of the conductive short fibers. The momentum of the conductive short fibers P=mv reflects the conductive short fibers. Implantation depth. The short conductive fiber also rotates around the fixed axis in the electric field. The equation of the orientation process is: Iθ″+MR (θ′)+ _{MP (θ)+M q (} θ) ₌ 0, I is the moment of inertia of the conductive short fiber , θ″ is the angular acceleration, θ′ is the angular velocity, θ is the angle between the long semi-axis direction and the external electric field E ₀ when the short conductive fiber just enters the electric field, M _R (θ′) is the damping moment of the medium, M _P (θ ) is the rotational torque generated by the polarized charge, M _q (θ) is the rotational torque generated by the induced charge, and the orientation process equation is related to the short conductive fiber itself, the applied field strength and the air resistance coefficient.

Preferably, the substrate material nozzle 1 can print materials that can be converted into a viscous fluid state, such as filaments, resins, and ceramic suspensions.

Preferably, the conductive short fibers include metal-based conductive fibers, polymer-based conductive fibers, carbon-based conductive fibers, composite conductive fibers, etc., and the resistivity is less than 10 ⁷ in a standard state (temperature is 20° C., relative humidity is 65%) Ω·cm fibers or other functional reinforcing materials.

Preferably, the conductive short fibers 7 should undergo fiber opening treatment to reduce the phenomenon of agglomeration.

Preferably, the orientation and implantation depth of the conductive short fibers are controlled by adjusting the applied field strength, the size and dielectric constant of the conductive short fibers.

Preferably, the high-voltage electrostatic generator 5 is equipped with a control box to control the change of voltage, and the size of the electric field is controlled by the control box to control the orientation and content of the conductive short fibers, and the conductive short fibers with different orientations are implanted into the matrix material 2 to form different gradients after curing.

Preferably, the voltage value of the high-voltage electrostatic generator 5 cannot be too large or too small. When the voltage value is lower than 30kV, the electric field strength is too small, and the external force on the conductive short fibers is too small, so that the conductive short fibers can only float on the surface, and the voltage When the value is higher than 60kV, the conductive short fibers are ionized, resulting in a discharge phenomenon, which affects the implantation process, and if the applied voltage is too high, the experiment will be unsafe. Preferably, the applied voltage values are 40kV, 50kV and 60kV.

Preferably, the structure-function oriented manufacturing is controlled by voltages in different areas and positions. The above-mentioned high-voltage electrostatic generator 5 itself is equipped with a control box to control the change of voltage. The magnitude of the voltage determines the content and direction of the conductive short fibers, so as to achieve different To enhance the effect, by presetting different codes on different types of conductive short fibers in different hoppers (similar to the codes in the automatic tool changing device of CNC machine tools), during the printing process, select the corresponding codes according to the instructions to input different types of conductive short fibers, In specific areas and positions, different types of conductive short fibers can be replaced according to the settings of the instructions to achieve different functions and realize the function-oriented manufacturing of the same part, such as electromagnetic shielding function, warpage suppression function, heat conduction function, etc. Through the above-mentioned control voltage and hopper switching, the structure and function of the same part can be manufactured with variable content (as shown in Figure 2), changed direction (as shown in Figure 3), and variable fibers (as shown in Figure 4).

Preferably, two or more sets of nested nozzles can be used, and two or more sets of nested nozzles can be used to achieve enhanced interlayer strength and simultaneous multi-material printing.

Finally, it should be noted that the above embodiments are only preferred embodiments of the present invention to illustrate the technical solutions of the present invention, not to limit them, and certainly not to limit the patent scope of the present invention; although referring to the foregoing embodiments The present invention has been described in detail, and those of ordinary skill in the art should understand that: it is still possible to modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements to some or all of the technical features; and these modifications or replacements , does not make the essence of the corresponding technical solution deviate from the scope of the technical solutions of the various embodiments of the present invention; that is to say, any change or refinement made in the main design idea and spirit of the present invention that has no substantial meaning, it solves the problem. If the technical problems of the present invention are still consistent with the present invention, they shall be included within the protection scope of the present invention; in addition, the technical solutions of the present invention are directly or indirectly applied in other related technical fields, and are similarly included in the protection scope of the present invention. within the scope of patent protection.

Claims (9)

1. The in-situ electronic control additive manufacturing device for the functional composite material is characterized by comprising one or more nested spray heads, wherein a printing substrate (3) is arranged below each nested spray head, each nested spray head comprises a base material spray head (1) for printing a base material (2), a strength-enhancing interlayer spray head (8) for implanting a functional enhancing material (7) into the base material (2) is sleeved outside each base material spray head (1), a plate-type metal mesh frame (6) is sleeved outside an outlet of each base material spray head (1), the plate-type metal mesh frame (6) is located at an outlet of each strength-enhancing interlayer spray head (8), the plate-type metal mesh frame (6) is connected to a high-voltage electrostatic generator (5) through a lead, and the high-voltage electrostatic generator (5) and the plate-type metal mesh frame (6) are matched to realize the direction and the position of implanting the functional enhancing material (7) into the base material (2), the high-voltage electrostatic generator (5) and the printing substrate (3) are both grounded (4).

2. The in-situ electronic control additive manufacturing device for functional composite materials according to claim 1, wherein the resistivity of the functional enhancement material (7) is less than 10 under a standard state ⁷ Ω·cm。

3. The in-situ electronic control additive manufacturing device for the functional composite material as claimed in claim 2, wherein the functional reinforcing material (7) is conductive short fiber.

4. The in-situ electronic control additive manufacturing device for functional composite materials according to claim 3, wherein the conductive short fibers are metal-based conductive fibers, polymer-based conductive fibers, carbon-based conductive fibers or composite conductive fibers.

5. The in-situ electronic control additive manufacturing device for functional composite materials according to claim 1, wherein the high voltage static generator (5) is configured with a control box for controlling voltage variation, and the voltage is used for determining the position and the direction of the functional reinforcing materials so as to realize different reinforcing effects.

6. The in-situ electronic control additive manufacturing device for functional composite materials according to claim 5, wherein the voltage value of the high voltage electrostatic generator (5) is 40-60 kV.

7. An in-situ electric control additive manufacturing process for a functional composite material, which adopts the device of claim 1, and is characterized in that while a matrix material spray head (1) prints, a functional enhancement material (7) is in contact with a plate-type metal mesh frame (6) which is electrified at an outlet of an enhancement interlayer strength spray head (8) to be electrified, the functional enhancement material (7) is polarized in an electric field, charges with the same polarity as that of the plate-type metal mesh frame (6) are concentrated at one end far away from the plate-type metal mesh frame (6), opposite charges are concentrated at one end close to the plate-type metal mesh frame (6), when the functional enhancement material (7) is in contact with the plate-type metal mesh frame (6), conductive current is generated in the functional enhancement material (7), the functional enhancement material (7) generates charges, and the functional enhancement material translates under the action of electrostatic force through controlling the external field intensity, the size and the dielectric constant of the functional enhancement material, The printing ink is rotated and periodically vibrated, and is implanted into a matrix material in a molten state according to a certain orientation, the matrix material in the molten state is solidified to fix the functional reinforcing material (7) in the matrix material, when the next layer is printed, the next layer of matrix material in the molten state completely covers and solidifies the functional reinforcing material (7), so that the connection between the layers is realized, in the printing process, the distance between the nested spray head and the printing matrix (3) is kept unchanged, and the matrix material (2) and the functional reinforcing material (7) are coaxially output and printed until a printed product is finished.

8. The in-situ electric control additive manufacturing process for the functional composite material as claimed in claim 7, wherein the functional reinforcing material (7) is conductive short fibers, and the conductive short fibers are subjected to fiber opening treatment before use.

9. The in-situ electric control additive manufacturing process of the functional composite material as claimed in claim 8, wherein the high voltage electrostatic generator (5) is matched with a control box for controlling voltage variation, the size of an electric field is controlled by the control box to further control the orientation and content of the functional reinforcing material, and different gradients are formed after the functional reinforcing materials with different orientations are implanted into the matrix material (2) and cured.

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