An apparatus and method for short fiber three-dimensional directional solidification molding

Abstract

This invention belongs to the field of curing and molding of short fiber composite materials, and discloses an apparatus and method for three-dimensional oriented curing and molding of short fibers. The orientation device of this invention includes a storage tank for holding the short fiber curing solution, a base for fixing the entire device, a horizontal rotation system for controlling the horizontal angle of the fibers, a vertical rotation system for controlling the vertical rotation angle of the fibers, and an electromagnetic system and a control system for providing an electromagnetic field. Under the command of the control system, the electromagnetic system generates an electromagnetic field, which is then used for magnetic field positioning under the drive of the horizontal and vertical rotation systems. The electromagnetic field then orients the magnetized short fibers. This apparatus and method can achieve three-dimensional orientation of short fibers in a matrix material, effectively improving the mechanical properties of short fiber reinforced composite materials and further enhancing the designability of short fiber composite materials.

Description

Technical Field

[0001] This invention relates to the field of curing and molding of short fiber composite materials, specifically to a device and method for three-dimensional orientation of short fibers assisted by a rotating electromagnetic field. Background Technology

[0002] Short fiber reinforced composites are characterized by simple manufacturing, ease of molding, flexible design, and low cost, making them a widely used type of composite material. While bringing opportunities to many industries, short fiber reinforced composites also face new requirements, thus necessitating a method for efficiently controlling material properties to adapt to different application scenarios.

[0003] In traditional curing processes, short fibers are randomly distributed within the matrix, making it impossible to determine their state. Therefore, achieving directional alignment of short fibers during curing would provide an effective approach for manufacturing materials with controllable properties. Invention patent CN201710147932.2 discloses a programmable directional short fiber reinforced composite material 3D printing method and apparatus. First, a scraper is used to evenly lay short fibers on the surface of the molding chamber, and then a permanent magnet is used to orient the short fibers in two dimensions within a plane. Invention patent CN201710264424.2 discloses a directional short fiber assembly 3D printing method and apparatus in a liquid matrix. Based on powder bed 3D printing, the orientation of the fibers is achieved by the shearing action of the scraper on the short fibers during material laying. Invention patent CN201810184327.7 discloses a directional short fiber reinforced metal or ceramic matrix composite material 3D printing method. A conical head is used to extrude a molten short fiber mixture along a specified path, and the shearing action of the inner wall of the extruder head transforms the short fibers from a disordered state to an ordered state.

[0004] In summary, the orientation devices or methods for short fiber composite materials still have the following problems, specifically:

[0005] (1) It is impossible to achieve multi-angle orientation of short fibers in three-dimensional space.

[0006] In short fiber composites, the fibers are mostly randomly distributed. While orientation in a two-dimensional plane has been achieved, it remains difficult to control their orientation in three-dimensional space. This limits the designability of composite materials and the improvement of product performance.

[0007] (2) Poor targeting effect and low controllability

[0008] The orientation function of extruders and scrapers is limited to short fibers in a localized area within a plane, and the degree of fiber orientation cannot be controlled as needed. The fibers can only be roughly aligned according to the direction of the extruder or scraper, and the orientation effect cannot be guaranteed. Furthermore, the fiber orientation is achieved through contact force, and the fiber direction cannot be changed as needed during the molding process, resulting in poor control precision and low flexibility. Summary of the Invention

[0009] This invention addresses the shortcomings of existing curing and molding devices and methods for short fiber reinforced composite materials, providing a device and method for three-dimensional oriented curing and molding of short fibers, based on practical engineering needs. This invention designs an electromagnetic device capable of rotation in three-dimensional space. The electromagnetic field excited by this device achieves multi-angle orientation of the short fibers during curing and molding. This advantage fully leverages the designability of short fiber reinforced composite materials, allowing control over the arrangement of short fibers according to actual requirements, and effectively improving the mechanical properties of the composite material.

[0010] To achieve the above, the present invention adopts the following technical solution:

[0011] The technical solution includes an apparatus for three-dimensional orientation curing of short fibers and a method for three-dimensional orientation curing of short fibers.

[0012] An apparatus for three-dimensional directional curing and molding of short fibers, such as Figure 1 The device shown mainly consists of a liquid storage tank 1, a base 2 coaxially mounted with the liquid storage tank 1, a horizontal rotation system 3 connected to the base 2 via a slide rail, a vertical rotation system 4 fixed on the horizontal rotation system 3, and an electromagnetic system 5 mounted on the vertical rotation system 4. The horizontal rotation system 3, the vertical rotation system 4, and the electromagnetic system 5 are all controlled and regulated by a control system 6.

[0013] In the device for three-dimensional directional curing of short fibers of the present invention, the liquid storage tank 1 has a deep groove structure with a circular or polygonal cross-section; when using rising photopolymerization 3D printing, the bottom of the liquid storage tank is a light-transmitting base plate; the fixed height of the liquid storage tank is adjusted according to the magnetic field height of the electromagnetic system.

[0014] In the device for three-dimensional orientation curing of short fibers of the present invention, the upper part of the base 2 has a groove that matches the slide rail on the lower surface of the track base plate 31, so that the track base plate 31 can freely rotate on the base 2.

[0015] The horizontal rotation system 3 in the apparatus for three-dimensional directional curing of short fibers of the present invention is as follows: Figure 2As shown, it includes a track base plate 31; an external gear 32 fixed to the track base plate 31 by a positioning structure; a horizontal transmission gear set 33 meshing with the external gear 32; and a horizontal drive motor 34 driving the horizontal transmission gear set 33. The horizontal drive motor 34 transmits the amplified torque to the external gear 32 after being reduced in speed by the horizontal transmission gear set 33. The transmission ratio of the horizontal transmission gear set 33 is determined according to the motor output value, the design parameters of the external gear 32, and the mass of the rotating parts.

[0016] The vertical rotation system 4 in the apparatus for three-dimensional directional curing of short fibers of the present invention is as follows: Figure 3 As shown, it includes a front support frame 41 and a rear support frame 42 fixed on the track base plate 31; a vertical drive motor 43 fixed on the front support 41; a front rotating frame 46 and a rear rotating frame 47 fixed on the upper ends of the front support frame 41 and the rear support frame 42; and a vertical transmission gear set 48 connecting the vertical drive motor 43 and the front rotating frame 46.

[0017] The electromagnetic system 5 in the apparatus for three-dimensional directional curing of short fibers of the present invention is as follows: Figure 4 As shown, it includes an iron core 51 and a coil assembly 52 wound around the iron core 51. The iron core 51 is clamped by a front rotating frame 46 and a rear rotating frame 47 at a relative angle of 180°, and can rotate at a certain angle about the center line of the two bearings at the upper end of the support frame as the rotation axis; a pair of magnetic poles are distributed on the inner side of the iron core 51 at a distance of 90° from the center line of the clamping part, each magnetic pole includes multiple teeth, and the inner side of the teeth is connected together by an arc-shaped panel; the coil is formed by closely winding enameled wire on the magnetic pole teeth side by side, and all the coils are wound in the same direction.

[0018] The control system 6 in the device for three-dimensional directional curing of short fibers of the present invention mainly consists of an upper computer and a lower computer, including a horizontal motor control part, a vertical motor control part and a magnetic field control part.

[0019] A method for three-dimensional orientation curing of short fibers includes the following steps: First, a curing method (such as 3D printing) is selected, and the curing process parameters are determined. Second, based on product performance requirements and the curing method, a curing matrix and short fiber materials are selected, and parameters such as the mechanical properties of the materials, the viscosity of the curing matrix, fiber content, and fiber length are determined. Then, a three-dimensional model of the product is created using CAD software, and the fiber angle and curing process parameters are optimized using CAE software. Simultaneously, magnetized short fibers are prepared and mixed with the curing matrix to form a curing solution. Next, a host computer control program is written based on the material properties, fiber angle, and curing process parameters. Before operation, the curing solution is poured into a storage tank, the device is adjusted to a suitable height, and the horizontal and vertical angles of the rotating device are zeroed. Then, the host computer transmits instructions to the slave computer to control parameters such as motor rotation angle and coil current. The horizontal drive motor controls the horizontal angle of the electromagnetic system, and the vertical drive motor controls the vertical angle of the electromagnetic system. Current is passed through the coil to form an electromagnetic field to guide the fiber orientation. Finally, appropriate post-processing is performed after the curing process is completed.

[0020] In the method for three-dimensional directional curing of short fibers of the present invention, the principle of fiber angle control is as follows: Figure 5 As shown. The horizontal rotation angle driven by the horizontal rotation system is:

[0021]

[0022] In the formula, α is the horizontal rotation angle, in rad; n h The speed of the horizontal drive motor is expressed in rpm; t h The running time of the horizontal drive motor is s; i h The transmission ratio of the horizontal transmission gear set; z h The number of teeth on the gear meshing with the external gear in the horizontal transmission gear set; z o This represents the number of teeth on the external gear. The vertical rotation angle driven by the vertical rotation system is:

[0023]

[0024] In the formula, β is the vertical rotation angle, in rad; n v The speed of the vertical drive motor is expressed in rpm; t v The running time of the vertical drive motor is s; i v This is the transmission ratio of the vertical transmission gear set.

[0025] In the method for three-dimensional orientation curing of short fibers according to the present invention, in order to ensure the shortest movement path of the fibers during the orientation process, the horizontal rotary motor and the vertical rotary motor need to move simultaneously, and to ensure that the running time is consistent, i.e., t h =t vThe speed relationship between the two motors is αn v =βn h After the coil is energized, the magnetic induction intensity at the end of the coil on a single tooth is:

[0026]

[0027] In the formula, B is the magnetic induction intensity (T); μ is the permeability of the iron core (T·m / A); N is the total number of turns of the coil; I is the excitation current in the coil (A); L is the length of the coil (m); and D is the average diameter of the coil (m). The electromagnetic field generated by the electromagnetic system is as follows: Figure 6 As shown, the short fiber rotates under the action of the magnetic field force, and its final direction is consistent with the direction of the magnetic induction lines in the liquid storage tank.

[0028] The beneficial effects of this invention are:

[0029] (1) By magnetizing short fibers of different materials and then introducing a magnetic field for fiber orientation, the performance of short fiber composite materials in various complex environments is effectively improved.

[0030] (2) It can achieve multi-angle orientation of short fibers in space through a three-dimensional rotating electric field, which increases the designability of short fiber composite materials.

[0031] (3) The orientation device and method are simple in principle. They achieve fiber orientation through electrical parameters and have advantages such as high precision, strong controllability and high orientation efficiency. Attached Figure Description

[0032] Figure 1 This is a three-dimensional structural diagram of the present invention.

[0033] Figure 2 This is a schematic diagram of the horizontal rotation system structure of the present invention.

[0034] Figure 3 This is a schematic diagram of the vertical rotation system structure of the present invention.

[0035] Figure 4 This is a schematic diagram of the electromagnetic system structure of the present invention.

[0036] Figure 5 This invention relates to the principle of achieving horizontal and vertical orientation of short fibers.

[0037] Figure 6 This is a magnetic field distribution diagram within the short fiber orientation plane of the present invention.

[0038] Figure 7 This is a structural diagram of a short fiber three-dimensional orientation device based on photopolymerization 3D printing, according to an embodiment of the present invention.

[0039] Explanation of reference numerals in the attached drawings: 1-Liquid reservoir; 2-Base; 3-Horizontal rotation system; 31-Rail base plate; 32-External gear; 33-Horizontal transmission gear set; 34-Horizontal drive motor; 4-Vertical rotation system; 41-Front support frame; 42-Rear support frame; 43-Vertical drive motor; 44-Bearing; 45-Locking component; 46-Front rotating frame; 47-Rear rotating frame; 48-Vertical transmission gear set; 5-Electromagnetic system; 51-Iron core; 52-Coil group; 6-Control system; 7-Photopolymer 3D printer; 71-Printing platform; 72-Lifting platform. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and examples. However, the embodiments of this invention are not limited thereto.

[0041] Example 1: This example uses photopolymer 3D printing as an example, where a short fiber orientation device is installed on a 3D printer to achieve fiber orientation in the composite material manufacturing process. For example... Figure 7 As shown, the short fiber orientation device is fixed to the printing platform 71 of the photopolymer 3D printer 7 via a base, and the fiber orientation is completed by adjusting some printing parameters during the molding process. The following are the specific implementation steps of this example:

[0042] 1. Design of an apparatus for three-dimensional directional curing of short fibers:

[0043] The mechanical structure of this device mainly consists of, for example... Figure 1 The structure consists of a liquid storage tank, a base, a horizontal rotating structure, a vertical rotating structure, and an electromagnetic structure.

[0044] like Figure 2 As shown, the top guide rail of the track base plate 31 and the bottom track of the base 2 are fully lubricated and can slide freely; the external gear 32 is fixed by a protrusion on the inner side that matches the groove on the outer edge of the track base plate 31; the horizontal drive motor 34 meshes with the external gear 32 through the horizontal transmission gear set 33.

[0045] like Figure 3 As shown, the vertical rotating structure is fixed in the groove on the track base plate 31 of the horizontal rotating system by the front support frame 41 and the rear support frame 42, and the two are fixed by screws or strong adhesive.

[0046] like Figure 4 As shown, the iron core 51 in the electromagnetic system is made of stacked silicon steel sheets, which are stamped according to the required shape; after the coil on each magnetic pole is wound, it is bound with insulating tape.

[0047] In this example, the motor, bearings, and locking rings are all standard parts; the gears are obtained by further processing the standard parts according to requirements; and the remaining parts are obtained by casting or additive manufacturing.

[0048] 2. Method for achieving three-dimensional directional curing and molding of short fibers:

[0049] Step 1: Select materials. In this example, the curing material is a photosensitive resin with a viscosity of 1000-1050 CPS at room temperature, and the reinforcing material is 0.1-1 mm long nickel-plated carbon fiber.

[0050] Step 2: Preparation of short fiber photosensitive resin solution. In a light-shielding environment, the magnetized carbon fiber is added to the resin solution, and the short fiber is uniformly distributed in the solution by mechanical stirring or other methods.

[0051] Step 3: Design the 3D model of the product in CAD software and import it into the slicing software; set the printer's forming parameters according to the material properties and forming requirements, and then import the file into the printer according to the specified format.

[0052] Step 4: After pouring the resin solution containing short fibers into the storage tank, start the control system; then zero the magnetic field position, that is, the horizontal rotation system is at the specified zero-degree position and the vertical rotation system is at the horizontal position.

[0053] Step 5: Input parameters α and β in the host computer software of the orientation control system according to the fiber angle (in this example, the fiber angle is set to α = 90°, β = 20°); then pass current through the coil (the current magnitude is proportional to the resin viscosity and fiber specific gravity). At this time, the fiber is rotated by the magnetic field and oriented to the zero position (α = 0°, β = 0°).

[0054] Step 6: After most fibers have reached the zero position, the orientation is initiated. The host computer will simultaneously send control commands to the horizontal and vertical rotary motors. At this time, the orientation information is converted into the rotation angle information of the motor shafts. After receiving the electrical signal controlled by the input angle α, the horizontal rotary motor drives the electromagnetic transducer to rotate horizontally. After receiving the electrical signal controlled by the input angle β, the vertical rotary motor drives the electromagnetic device to rotate vertically. The electromagnetic device rotates in both the horizontal and vertical directions at the same time, and the fibers will be oriented by following the rotating electromagnetic field.

[0055] Step 7: After a certain period of time, once the fiber orientation is complete, start the 3D printer; if the fiber orientation needs to be changed during the printing process, repeat step 6.

[0056] Step 8: After printing is complete, perform post-processing work such as secondary curing on the model.

[0057] The interlaminar toughness (between two adjacent cured regions) of the short fiber composite material prepared in this example was significantly enhanced, and the directional reinforcing effect of the fibers was significant.

Claims

1. An apparatus for three-dimensional directional curing and molding of short fibers, characterized in that, The device for three-dimensional orientation curing of short fibers includes a liquid storage tank (1), a base (2) coaxially mounted with the liquid storage tank (1), a horizontal rotation system (3) connected to the base (2) via a slide rail, a vertical rotation system (4) fixed on the horizontal rotation system (3), and an electromagnetic system (5) mounted on the vertical rotation system (4); wherein the horizontal rotation system (3), the vertical rotation system (4), and the electromagnetic system (5) are all controlled and regulated by a control system (6); the horizontal rotation system (3) includes a track base plate (31), an external gear (32) fixed to the track base plate (31) via a concave-convex positioning structure, a horizontal transmission gear set (33) meshing with the external gear (32), and a horizontal drive motor (34) driving the horizontal transmission gear set (33); the horizontal drive motor (34) is decelerated by the horizontal transmission gear set (33). The amplified torque is then transmitted to the external gear (32). The transmission ratio of the horizontal transmission gear set (33) is determined according to the motor output value, the design parameters of the external gear (32), and the mass of the rotating component. The vertical rotation system (4) includes a front support frame (41) and a rear support frame (42) fixed on the track base plate (31), a vertical drive motor (43) fixed on the front support frame (41), a front rotating frame (46) and a rear rotating frame (47) fixed to the upper ends of the front support frame (41) and the rear support frame (42) respectively by bearings (44) and locking parts (45), and a vertical transmission gear set (48) connecting the vertical drive motor (43) and the front rotating frame (46). The electromagnetic system (5) includes an iron core (51) clamped and fixed by the front rotating frame (46) and the rear rotating frame (47) and a coil set (52) wound on the iron core (51).

2. The apparatus according to claim 1, characterized in that, The upper part of the base (2) has a groove that matches the slide rail on the lower surface of the track base plate (31), so that the track base plate (31) can freely rotate on the base (2).

3. The apparatus according to claim 1, characterized in that, The front support frame (41) and the rear support frame (42) are fixed on the track base plate (31) of the horizontal rotation system (3). The upper ends of the front support frame (41) and the rear support frame (42) are equipped with bearings (44). The inner ring of the bearing is fixed to the front rotating frame (46) and the rear rotating frame (47) by locking parts (45). The vertical drive motor (43) is fixed to the front support frame (41) by bolts and transmits torque to the front rotating frame (46) through the vertical transmission gear set (48).

4. The apparatus according to any one of claims 1-3, characterized in that, The iron core (51) is fixed by the grooves at the ends of the front rotating frame (46) and the rear rotating frame (47); and the iron core (51), the front rotating frame (46) and the rear rotating frame (47) are rotated as a whole on the vertical rotating system (4) by the bearing (44) and the locking member (45).

5. The apparatus according to claim 4, characterized in that, The iron core (51) is made of soft magnetic material and contains symmetrically distributed magnetic poles, with the effective working area between the magnetic poles being fiber orientation; the coil group (52) is wound around the magnetic pole teeth of the iron core (51), each magnetic pole has multiple teeth, and each tooth is wound with a coil; the iron core (51) and the coil group (52) thereon can rotate in both the plane and the vertical plane.

6. The device according to claim 1 is characterized in that, The control system (6) mainly consists of a host computer and a slave computer, including a horizontal motor control section, a vertical motor control section and a magnetic field control section.

7. A method for three-dimensional directional curing of short fibers, based on the apparatus for three-dimensional directional curing of short fibers according to claim 1, characterized in that, First, a liquid curing material mixed with short fibers is added to the storage tank (1); second, the control system (6) calculates the control signal of the motor according to the preset fiber angle, gear transmission ratio and motor speed, and sends the signal to the horizontal drive motor (34) and the vertical drive motor (43); then, the electromagnetic system (5) reaches the designated position and direction under the drive of the horizontal drive motor (34) and the horizontal transmission gear set (33), the vertical drive motor (43) and the vertical transmission gear set (48); finally, the control system (6) controls the magnitude and energizing time of the current in the coil group (52) according to the properties of the liquid curing material and the fiber. The magnitude and energizing time need to be determined by testing the fiber before molding; during operation, the control system (6) periodically sends control signals to the drive motor and the coil to achieve real-time orientation of the short fibers throughout the curing cycle.

8. The method according to claim 7, characterized in that, The curing and molding process includes thermosetting, photosetting, electron beam curing and microwave curing, and the matrix used for curing is liquid resin.

9. The method according to claim 7, characterized in that, The short fibers need to be magnetized by sputtering, ion plating, chemical plating, or powder coating to form a layer of iron oxide, nickel, or copper film on the surface of the short fibers, so that the short fibers can be subjected to directional electromagnetic force in a magnetic field.

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