Thermosetting resin matrix composite 3D printing device and printing method

Abstract

The invention discloses a thermosetting resin matrix composite 3D printing device and method, and belongs to the technical field of composite forming. The thermosetting resin-based composite material 3D printing device comprises a fiber feeding unit, a resin feeding unit and a confluence unit which are arranged on a fixing frame; the confluence unit comprises a confluence pipe and a printing spray head, the printing spray head is located below the confluence pipe, continuous fibers and thermosetting resin are mixed in the confluence pipe and subjected to in-situ dipping coating in the printing spray head, and the continuous fibers and the thermosetting resin are extruded through the printing spray head to be formed on a printing platform; and a heating curing structure is arranged at the bottom of the printing nozzle, and in-situ curing of the composite material is achieved through the heating curing structure. By means of the thermosetting resin matrix composite 3D printing device and method, the problems that existing thermosetting resin printing procedures are complex, performance is poor, and adaptability is poor can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite material forming, in particular to a thermosetting resin-based composite material 3D printing device and printing method. BACKGROUND

[0002] Continuous fiber reinforced resin-based composite materials have excellent specific strength, specific stiffness, thermal stability, corrosion resistance, lightweight and other characteristics, and are widely used in the fields of aviation, aerospace, vehicles, energy, construction, shipbuilding and the like. Compared with continuous carbon fiber reinforced thermoplastic composite materials, continuous carbon fiber reinforced thermosetting composite materials have better strength, hardness, heat resistance and corrosion resistance; in particular, the initial viscosity of the thermosetting resin is low, the wettability with the fiber is good, and the interlayer bonding strength is high, which becomes the main choice for high-performance composite material components.

[0003] In recent years, 3D printing of continuous reinforced resin-based composite materials has mainly focused on thermoplastic resin matrix, while thermosetting resin is difficult to match the curing and printing speed due to its long gel and curing time, so it is more difficult to achieve 3D printing. At present, the printing principle for 3D printing of fiber-reinforced thermosetting composite materials mainly focuses on adjusting the rheological properties of the thermosetting resin system, adding a viscosity modifier to the resin material system to make it have thixotropy, i.e. it becomes thin during extrusion and shear, and restores viscosity after shear stops, thereby forming, and then post-curing, but it has the disadvantages of unstable printing process, weak interlayer bonding and easy deformation during post-curing. Light-cured resin or light / heat co-cured dual-phase resin can also be used, which uses ultraviolet light to cause rapid in-situ curing of the light-sensitive resin to shape. However, this method relies on light-cured resin, which usually has the disadvantages of low strength, poor weather resistance and poor aging resistance. In addition, there is a method of first immersing the fiber in a thermosetting resin pool, then printing through a nozzle after immersion is complete, and then performing preliminary curing through a hot air gun after extrusion, and then post-curing in an oven after printing is complete. However, the hot air gun in this method can only perform single-point curing of the extruded resin from a single direction, the curing is uneven and the curing range is small, the curing process is complex, and it is difficult to produce complex workpieces. SUMMARY

[0004] The purpose of the present application is to provide a thermosetting resin-based composite material 3D printing device and printing method, which solves the problems of complex printing process, poor performance and poor adaptability of existing thermosetting resin.

[0005] In order to achieve the above-mentioned purpose, the application provides a thermosetting resin-based composite material 3D printing device, which comprises a fiber feeding unit, a resin feeding unit and a confluence unit arranged on a fixing frame, the resin feeding unit is located on one side of the fiber feeding unit; the confluence unit comprises a confluence pipe and a printing nozzle, the printing nozzle is located below the confluence pipe, the resin outlet of the resin feeding unit is connected with the resin inlet of the confluence pipe, the fiber outlet of the fiber feeding unit is connected with the fiber inlet of the confluence pipe, the continuous fiber and the thermosetting resin are mixed in the confluence pipe and in-situ impregnated and coated in the printing nozzle, the impregnated and coated composite material is extruded on the printing platform through the printing nozzle; the bottom of the printing nozzle is provided with a heating and curing structure, which realizes in-situ curing of the composite material.

[0006] Preferably, the outside of the printing nozzle is provided with a cooling structure, the cooling structure is sleeved on the outer wall of the printing nozzle, the heating and curing structure is arranged above the nozzle of the printing nozzle, the cooling structure is arranged upstream of the heating and curing structure, and a heat insulation layer is arranged between the cooling structure and the heating and curing structure.

[0007] Preferably, the cooling structure comprises a condensing pipe, the condensing pipe is sleeved on the outer wall of the printing nozzle, the inside of the condensing pipe is provided with a spiral cooling flow channel, and the cooling flow channel is in communication with an external cooling liquid circulating device.

[0008] Preferably, the heating and curing structure comprises an annular ceramic heating sheet, the distance between the ceramic heating sheet and the nozzle is 0.3mm-5mm, the inner diameter of the ceramic heating sheet is 1mm-20mm, and the outer diameter of the ceramic heating sheet is 10mm-50mm.

[0009] Preferably, the fiber feeding unit comprises a fiber storage mechanism, a catheter is arranged below the fiber storage mechanism, the fiber storage mechanism is connected with the confluence pipe through the catheter, the fiber storage mechanism, the catheter and the confluence pipe are on the same straight line, and the fiber in the fiber storage mechanism enters the confluence pipe through the catheter; the fiber storage mechanism comprises a box body, a roller shaft is rotatably arranged in the box body, the fiber is wound on the roller shaft, an end cover for closing the box body is arranged at the top of the box body, the end cover and the box body are sealingly connected through a sealing ring, an opening for the fiber to pass through the box body is arranged on the box body, and the catheter is arranged at the opening.

[0010] Preferably, the resin feeding unit comprises a barrel, a pressure source for sending the resin in the barrel into the confluence pipe is arranged at the top end of the barrel, the bottom end outlet of the barrel is connected with the resin inlet of the confluence pipe, and the barrel is located on one side of the confluence pipe.

[0011] Preferably, the fixing frame comprises a fixing plate, a first fixing ring and a second fixing ring for fixing the resin feeding unit are arranged on one side of the fixing plate, and a fixing seat for fixing the fiber feeding unit is arranged on the other side of the fixing plate.

[0012] The printing method of the thermosetting resin-based composite material 3D printing device comprises the following steps: S1, the thermosetting resin material is loaded into the barrel, the continuous fiber is loaded into the box body, and the end is covered, the fiber is pulled out of the box body to the catheter, and is led out through the manifold and the printing nozzle; S2, start the cooling liquid circulating device, and the cooling liquid cools the printing nozzle through the condenser pipe; start the ceramic heating sheet, so that the ceramic heating sheet reaches the resin curing temperature of 200-400 DEG C; S3, start the pressure source, the pressure source sends the thermosetting resin in the barrel into the manifold, the thermosetting resin is mixed with the fiber in the manifold, and is together into the printing nozzle, the condenser pipe cools the thermosetting resin, keeps the fluidity of the thermosetting resin, improves the impregnation effect, and the thermosetting resin and the fiber in the printing nozzle are extruded from the nozzle and deposited on the printing platform; S4, the printing nozzle moves on the printing platform, the ceramic heating sheet heats and cures the thermosetting resin on the printing platform in situ, and the composite material is shaped.

[0013] Preferably, in S1, the thermosetting resin material comprises the following components by mass fraction: thermosetting resin 100 parts, latent curing agent 5-15 parts, rheological modifier 1-10 parts; the thermosetting resin is one of epoxy resin, unsaturated polyester, cyanate ester resin, methyl methacrylate, dicyclopentadiene resin, the latent curing agent is one of imidazole, amine, dicyandiamide, ionic liquid, benzoyl peroxide and azobisisobutyronitrile, the rheological modifier is one of nano clay and nanosilica; the fiber is one of carbon fiber, glass fiber, Kevlar fiber, ceramic fiber and natural plant fiber, and the fiber tows are 1K, 3K, 6K or 12K.

[0014] Preferably, in S2, the condenser pipe keeps the temperature of the thermosetting resin in the printing nozzle at 20-80 DEG C; in S4, the printing moving speed of the printing nozzle is 25 -150 , the printing interval is 0.8-1.2 times the diameter of the nozzle, and the layer thickness is 0.5-1.1 times the diameter of the nozzle.

[0015] The thermosetting resin-based composite material 3D printing device and the printing method have the following advantages and positive effects: 1. This invention incorporates a condenser tube and a ring-shaped ceramic heating element on the printhead. The condenser tube controls the temperature of the thermosetting resin within the printhead, adjusting its viscosity and improving the impregnation and encapsulation effect between the resin and fibers. The ceramic heating element performs in-situ curing of the thermosetting resin on the printing platform, enhancing printing accuracy and forming speed. Direct in-situ curing via the ceramic heating element eliminates the need for subsequent curing processes, simplifying the process and facilitating faster printing.

[0016] 2. The 3D printing device of this invention is fixed on a frame, has a simple structure, and moves via the frame, enabling the printing of workpieces of various shapes. Based on the principle of heat curing, this invention is applicable to a variety of engineering thermosetting resins and their composites, exhibiting wide material applicability. Furthermore, the resin of this invention has good fluidity, good fiber-resin wettability, and good interlayer bonding performance in the molded parts.

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the 3D printing device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the wire storage mechanism according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the printing principle according to an embodiment of the present invention; Figure 4 This is a physical image of the printed sample from Embodiment 2 of the present invention; Figure 5 This is a cross-sectional CT image of the printed sample of Embodiment 2 of the present invention; Figure 6 This is a SEM image of the interlayer cross-section of the printed sample in Embodiment 2 of the present invention; Figure 7 This is a flowchart of the printing method according to an embodiment of the present invention.

[0019] Figure Labels 1. Fiber storage mechanism; 11. End cap; 12. Sealing ring; 13. Roller; 14. Box body; 2. Conduit; 3. Manifold; 4. Printer nozzle; 5. Condenser tube; 6. Ceramic heating element; 7. Fixing frame; 71. First fixing ring; 72. Fixing plate; 73. Fixing base; 74. Second fixing ring; 8. Resin feeding unit; 81. Pressure source; 82. Material cylinder. Detailed Implementation

[0020] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present application is usually placed, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "arrangement", "installation", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0021] In the present application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as understood by those skilled in the art to which the present application belongs. If there is any inconsistency, the meaning described in the specification or derived from the content described in the specification shall prevail. In addition, the terms used herein are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.

[0022] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0023] As Figure 1 shown, a thermosetting resin-based composite 3D printing device includes a fiber feeding unit, a resin feeding unit 8 and a confluence unit arranged on a fixed frame 7, the resin feeding unit 8 is located on one side of the fiber feeding unit. The fixed frame 7 includes a fixed plate 72, one side of the fixed plate 72 is provided with a first fixing ring 71 and a second fixing ring 74, the first fixing ring 71 fixes the upper end of the barrel 82, the second fixing ring 74 fixes the lower end of the barrel 82, which improves the stability of the barrel 82 fixed on the fixed frame 7. The first fixing ring 71 and the second fixing ring 74 can be hinged at one end with the fixed plate 72, and the other end is fixedly connected with the fixed plate 72 through screws, which facilitates the installation and disassembly of the barrel 82. The other side of the fixed plate 72 is provided with a fixing seat, the yarn storage mechanism 1 and the guide pipe 2 are fixed on the fixed plate 72. The fixed frame 7 can be fixed on the existing mobile module to realize the movement and rotation in X, Y and Z directions, and realize the flexible movement and rotation of the 3D printing device.

[0024] The confluence unit comprises a confluence pipe 3 and a printing nozzle 4, and the printing nozzle 4 is located below the confluence pipe 3. The confluence pipe 3 is a three-way structure, and two inlets thereof are connected with a resin feeding unit 8 and a fiber feeding unit, respectively, and an outlet thereof is connected with the printing nozzle 4. The resin outlet of the resin feeding unit 8 is connected with the resin inlet of the confluence pipe 3, and the fiber outlet of the fiber feeding unit is connected with the fiber inlet of the confluence pipe 3. The continuous fiber and the thermosetting resin are mixed in the confluence pipe 3 and in-situ impregnated and coated in the printing nozzle 4, and the impregnated and coated composite material is extruded on the printing platform through the printing nozzle 4. The caliber of the nozzle is 0.1mm-2mm.

[0025] The printing nozzle 4 is externally provided with an auxiliary forming mechanism. The auxiliary forming mechanism comprises a cooling structure and a heating and curing structure, and the cooling structure is arranged upstream of the heating and curing structure. The cooling structure is sleeved on the outer wall of the printing nozzle 4, and is used for cooling the thermosetting resin in the printing nozzle 4, so as to avoid the temperature rise from causing the thermosetting resin to be cured, and to improve the flowability of the thermosetting resin and the uniformity of the impregnated and coated fiber. The heating and curing structure is arranged above the nozzle of the printing nozzle 4, and is used for curing the composite material on the printing platform in-situ, so as to improve the precision and the accuracy and stability of the structure of the printing. A heat insulation layer is arranged between the cooling structure and the heating and curing structure, so as to reduce the temperature influence between the heating and curing structure and the cooling structure.

[0026] The cooling structure comprises a condenser pipe 5, and the condenser pipe 5 is sleeved on the outer wall of the printing nozzle 4. The condenser pipe 5 is internally provided with a spiral cooling flow channel, and the cooling flow channel is in communication with an external cooling liquid circulating device. The cooling liquid circulating device can adopt an existing structure as required.

[0027] The heating and curing structure comprises an annular ceramic heating sheet 6, and the distance between the ceramic heating sheet 6 and the nozzle is 0.3mm-5mm. The inner diameter of the ceramic heating sheet 6 is 1mm-20mm, and the outer diameter of the ceramic heating sheet 6 is 10mm-50mm. The heating temperature of the ceramic heating sheet 6 is not less than 300℃. The annular ceramic heating sheet 6 can sufficiently cover and cure the composite material on the printing platform, the local high-strength thermal field can make the thermosetting resin quickly gel and cure, improve the curing effect of the thermosetting resin, promote the in-situ curing of the thermosetting resin, and is beneficial to improving the speed of 3D printing.

[0028] As Figure 2As shown, the fiber feeding unit includes a yarn storage mechanism 1, a conduit 2 is arranged below the yarn storage mechanism 1, and the yarn storage mechanism 1 is connected to the manifold 3 through the conduit 2. The yarn storage mechanism 1, the conduit 2, the manifold 3 and the printing nozzle 4 are on the same straight line, ensuring the uniform and smooth movement of the fiber. The fiber in the yarn storage mechanism 1 enters the manifold 3 through the conduit 2. The yarn storage mechanism 1 includes a box body 14, a roller shaft 13 is rotatably arranged in the box body 14, and the roller shaft 13 is located in the grooves on both sides of the box body 14, facilitating the installation and removal of the roller shaft 13. The fiber is wound on the roller shaft 13. The top of the box body 14 is provided with an end cover 11 for closing the box body 14, and the end cover 11 and the box body 14 are sealingly connected through a sealing ring 12. An opening is provided on the box body 14 for the fiber to pass through the box body 14, and the conduit 2 is arranged at the opening. An opening is provided on the end cover 11, and a power source can be arranged above the end cover 11 to assist the movement of the fiber. The movement of the fiber during printing is mainly through the dragging of the printing device.

[0029] The resin feeding unit 8 includes a barrel 82, and a pressure source 81 is arranged at the top end of the barrel 82 to feed the resin in the barrel 82 into the manifold 3. The bottom end outlet of the barrel 82 is connected to the resin inlet of the manifold 3, and the barrel 82 is located on one side of the manifold 3. The pressure source 81 is an existing gas pressure, screw or plunger type extrusion system. The gas pressure system includes an air compressor and a gas flow rate controller, the screw extrusion system includes a servo motor and an extrusion screw, and the plunger extrusion system includes a driving motor and an extrusion piston.

[0030] As shown in Figure 3 , Figure 7 The printing method of the thermosetting resin-based composite 3D printing device includes the following steps: S1, the thermosetting resin material is loaded into the barrel 82, the continuous fiber is loaded into the box body 14, and the end cover is covered, the fiber is pulled out of the box body 14 to the conduit 2, and is led out through the manifold 3 and the printing nozzle 4.

[0031] The thermosetting resin material includes the following components by mass fraction: thermosetting resin 100 parts, latent curing agent 5-15 parts, and rheological modifier 1-10 parts. The thermosetting resin is one of epoxy resin, unsaturated polyester, cyanate ester resin, methyl methacrylate, and dicyclopentadiene resin. The latent curing agent is one of imidazole, amine, dicyandiamide, ionic liquid, benzoyl peroxide, and azobisisobutyronitrile. The rheological modifier is one of nano clay and nano silicon dioxide. The fiber is one of carbon fiber, glass fiber, Kevlar fiber, ceramic fiber and natural plant fiber, and the fiber tows are 1K, 3K, 6K or 12K.

[0032] The thermosetting resin material can be stably stored at room temperature, and can be quickly gelled and cured after being heated to the curing temperature.

[0033] S2, start the cooling liquid circulating device, the cooling liquid cools the printing nozzle 4 through the condenser tube 5, and the condenser tube 5 keeps the temperature of the thermosetting resin in the printing nozzle 4 at 20-80℃. Start the ceramic heating sheet 6, and make the ceramic heating sheet 6 reach the resin curing temperature of 200-400℃.

[0034] S3, start the pressure source 81, and the pressure source 81 sends the thermosetting resin in the barrel 82 into the manifold 3, the thermosetting resin is mixed with the fiber in the manifold 3, and then enters the printing nozzle 4 together, and then performs impregnation and coating in the printing nozzle 4, the condenser tube 5 cools the thermosetting resin, keeps the fluidity of the thermosetting resin, improves the impregnation effect, and the thermosetting resin and the fiber in the printing nozzle 4 are extruded from the nozzle and deposited on the printing platform.

[0035] S4, the printing nozzle 4 moves on the printing platform, the ceramic heating sheet 6 performs in-situ heating and curing on the thermosetting resin on the printing platform, and the composite material is shaped. The printing moving speed of the printing nozzle 4 is 25 -150 . The printing interval is 0.8-1.2 times the diameter of the nozzle, and the layer thickness is 0.5-1.1 times the diameter of the nozzle. At the corner of the printing path, the printing moving speed is adjusted, the speed is increased before entering the corner to reduce material accumulation, and the speed is decreased after turning out of the corner to fill the material depression.

[0036] Example 1 The printing method of the thermosetting resin-based composite material 3D printing device comprises the following steps: S1, mix the epoxy resin, imidazole curing agent and nano clay together according to the mass ratio of 100:10:8, and then put them into the barrel 82; put the continuous carbon fiber with a filament diameter of 1K into the box body 14 and pull it into the manifold 3; and finally lead out from the nozzle with a diameter of 0.7mm.

[0037] S2, start the cooling liquid circulating device, and the cooling liquid cools the printing nozzle 4 through the condenser tube 5. Start the ceramic heating sheet 6, and make the ceramic heating sheet 6 reach the resin curing temperature of 250℃.

[0038] S3, start the pressure source 81, and the pressure source 81 sends the thermosetting resin in the barrel 82 into the manifold 3, the thermosetting resin is mixed with the fiber in the manifold 3, and then enters the printing nozzle 4 together, and then performs impregnation and coating in the printing nozzle 4, the condenser tube 5 cools the thermosetting resin, keeps the fluidity of the thermosetting resin, improves the impregnation effect, and the thermosetting resin and the fiber in the printing nozzle 4 are extruded from the nozzle and deposited on the printing platform.

[0039] S4, the printing nozzle 4 moves on the printing platform, and the ceramic heating sheet 6 performs in-situ heating and curing on the thermosetting resin on the printing platform to shape the composite material. The printing moving speed of the printing nozzle 4 is 50 mm / min, the printing interval is 0.6 mm, and the layer thickness is 0.5 mm.

[0040] Embodiment 2 The printing method of the thermosetting resin-based composite material 3D printing device comprises the following steps: S1, the epoxy resin, the imidazole curing agent and the nano clay are mixed together according to the mass ratio of 100:10:6 and loaded into the barrel 82; the continuous carbon fiber with a filament diameter of 1K is loaded into the box body 14 and pulled into the manifold 3; and finally, it is drawn out from the nozzle with a diameter of 0.5 mm.

[0041] S2, start the cooling liquid circulating device, and the cooling liquid cools the printing nozzle 4 through the condenser pipe 5. Start the ceramic heating sheet 6, so that the ceramic heating sheet 6 reaches the resin curing temperature of 220 DEG C.

[0042] S3, start the pressure source 81, the pressure source 81 sends the thermosetting resin in the barrel 82 into the manifold 3, the thermosetting resin and the fiber are mixed in the manifold 3, and then enter the printing nozzle 4 together, and then the printing nozzle 4 is immersed and coated, the condenser pipe 5 cools the thermosetting resin, keeps the fluidity of the thermosetting resin, improves the immersion effect, and the thermosetting resin and the fiber in the printing nozzle 4 are extruded from the nozzle and deposited on the printing platform.

[0043] S4, the printing nozzle 4 moves on the printing platform, and the ceramic heating sheet 6 performs in-situ heating and curing on the thermosetting resin on the printing platform to shape the composite material. The printing moving speed of the printing nozzle 4 is 50 mm / min, the printing interval is 0.5 mm, and the layer thickness is 0.3 mm.

[0044] Embodiment 3 The printing method of the thermosetting resin-based composite material 3D printing device comprises the following steps: S1, the epoxy resin, the imidazole curing agent and the nano clay are mixed together according to the mass ratio of 100:12:8 and loaded into the barrel 82; the continuous carbon fiber with a filament diameter of 1K is loaded into the box body 14 and pulled into the manifold 3; and finally, it is drawn out from the nozzle with a diameter of 0.7 mm.

[0045] S2, start the cooling liquid circulating device, and the cooling liquid cools the printing nozzle 4 through the condenser pipe 5. Start the ceramic heating sheet 6, so that the ceramic heating sheet 6 reaches the resin curing temperature of 220 DEG C.

[0046] S3, start the pressure source 81, the pressure source 81 sends the thermosetting resin in the barrel 82 into the manifold 3, the thermosetting resin is mixed with the fiber in the manifold 3, and is together into the printing nozzle 4, carries out the impregnation and the coating in the printing nozzle 4, the condenser pipe 5 carries out cooling to the thermosetting resin, keeps the fluidity of the thermosetting resin, improves the impregnation effect, and the thermosetting resin and the fiber in the printing nozzle 4 are extruded from the nozzle and deposited on the printing platform.

[0047] S4, the printing nozzle 4 moves on the printing platform, the ceramic heating sheet 6 carries out in situ heating and curing to the thermosetting resin on the printing platform, and the composite material is shaped.The printing moving speed of the printing nozzle 4 is 50 mm / min, the moving speed at the corner is 65mm / min, the printing interval is 0.6mm, and the layer thickness is 0.5mm.

[0048] Example 4 The printing method of the thermosetting resin-based composite material 3D printing device comprises the following steps: S1, the epoxy resin, imidazole curing agent and nano clay are mixed together according to the mass ratio of 100:10:8 and loaded into the barrel 82;The continuous carbon fiber with a filament diameter of 3K is loaded into the box body 14 and is drawn into the manifold 3;Finally, it is drawn from the nozzle with a diameter of 1.2mm.

[0049] S2, start the cooling liquid circulating device, and the cooling liquid cools the printing nozzle 4 through the condenser pipe 5.Start the ceramic heating sheet 6, so that the ceramic heating sheet 6 reaches the resin curing temperature of 250℃.

[0050] S3, start the pressure source 81, the pressure source 81 sends the thermosetting resin in the barrel 82 into the manifold 3, the thermosetting resin is mixed with the fiber in the manifold 3, and is together into the printing nozzle 4, carries out the impregnation and the coating in the printing nozzle 4, the condenser pipe 5 carries out cooling to the thermosetting resin, keeps the fluidity of the thermosetting resin, improves the impregnation effect, and the thermosetting resin and the fiber in the printing nozzle 4 are extruded from the nozzle and deposited on the printing platform.

[0051] S4, the printing nozzle 4 moves on the printing platform, the ceramic heating sheet 6 carries out in situ heating and curing to the thermosetting resin on the printing platform, and the composite material is shaped.The printing moving speed of the printing nozzle 4 is 50 mm / min, the moving speed at the corner is 65mm / min, the printing interval is 1mm, and the layer thickness is 0.8mm.

[0052] Example 5 The printing method of the thermosetting resin-based composite material 3D printing device comprises the following steps: S1, the epoxy resin, imidazole curing agent, nanoclay are mixed together according to the mass ratio of 100:10:8 and loaded into the barrel 82; the continuous carbon fiber with a filament diameter of 1K is loaded into the box body 14 and pulled into the manifold 3; finally, it is drawn from the nozzle with a diameter of 0.9mm.

[0053] S2, start the cooling liquid circulating device, the cooling liquid cools the printing nozzle 4 through the condenser pipe 5. Start the ceramic heating sheet 6, so that the ceramic heating sheet 6 reaches the resin curing temperature of 250℃.

[0054] S3, start the pressure source 81, the pressure source 81 sends the thermosetting resin in the barrel 82 into the manifold 3, the thermosetting resin is mixed with the fiber in the manifold 3, and then enters the printing nozzle 4 together, and then is immersed and coated in the printing nozzle 4, the condenser pipe 5 cools the thermosetting resin, keeps the fluidity of the thermosetting resin, improves the immersion effect, and the thermosetting resin and the fiber in the printing nozzle 4 are extruded from the nozzle and deposited on the printing platform.

[0055] S4, the printing nozzle 4 moves on the printing platform, the ceramic heating sheet 6 heats and cures the thermosetting resin on the printing platform in situ, and shapes the composite material. The printing moving speed of the printing nozzle 4 is 50 mm / min, the moving speed at the corner is 65mm / min, the printing interval is 0.9mm, and the layer thickness is 0.6mm.

[0056] For the above embodiment, the performance of part of the sample is tested. The printing sample of example 2 is shown in Figure 4 , and the tensile strength can reach 450 MPa, as shown in table 1. The microstructure of the printing sample of example 2 is analyzed by scanning electron microscope (SEM), computer tomography (CT) and other microcharacterization methods. The CT image of the sample is shown in Figure 5 , and the fiber content is 20% and the porosity is less than 1% measured by cross-sectional gray scale statistics. The results show that the porosity of the sample formed by the printing method is low. Figure 6 The SEM image of the interlayer fracture surface of the printing sample of example 2 is shown in

[0057] Table 1 tensile properties of printing sample

[0058] Therefore, by using the thermosetting resin-based composite 3D printing device and printing method, the problems of complex printing process, poor performance and poor adaptability of the existing thermosetting resin can be solved.

[0059] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application but not to limit it, and although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can still be modified or replaced equivalently, and these modifications or equivalent replacements should not make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A 3D printing device for thermosetting resin-based composite materials, characterized in that: The system includes a fiber feeding unit, a resin feeding unit, and a manifold unit mounted on a fixed frame. The resin feeding unit is located to one side of the fiber feeding unit. The manifold unit includes a manifold tube and a print head, with the print head located below the manifold tube. The resin outlet of the resin feeding unit is connected to the resin inlet of the manifold tube, and the fiber outlet of the fiber feeding unit is connected to the fiber inlet of the manifold tube. Continuous fibers and thermosetting resin are mixed inside the manifold tube and in-situ impregnated and coated inside the print head. The impregnated and coated composite material is extruded through the print head onto a printing platform to form a composite material. A heat curing structure is provided at the bottom of the print head to achieve in-situ curing of the composite material.

2. The thermosetting resin-based composite material 3D printing device according to claim 1, characterized in that: The print head is provided with a cooling structure on its exterior, which is sleeved on the outer wall of the print head. The heating and curing structure is located above the nozzle of the print head, and the cooling structure is located upstream of the heating and curing structure. A heat insulation layer is provided between the cooling structure and the heating and curing structure.

3. The thermosetting resin-based composite material 3D printing device according to claim 2, characterized in that: The cooling structure includes a condenser tube, which is sleeved on the outer wall of the print head. The condenser tube has a spiral cooling channel inside, which is connected to an external coolant circulation device.

4. The thermosetting resin-based composite material 3D printing device according to claim 2, characterized in that: The heating and curing structure includes an annular ceramic heating element, the distance between the ceramic heating element and the nozzle is 0.3mm-5mm, the inner diameter of the ceramic heating element is 1mm-20mm, and the outer diameter of the ceramic heating element is 10mm-50mm.

5. The thermosetting resin-based composite material 3D printing device according to claim 1, characterized in that: The fiber feeding unit includes a fiber storage mechanism, with a conduit located below the fiber storage mechanism. The fiber storage mechanism is connected to a manifold via the conduit, and the fiber storage mechanism, conduit, and manifold are aligned in a straight line. Fibers in the fiber storage mechanism enter the manifold through the conduit. The fiber storage mechanism includes a box body, with a roller rotatably mounted inside the box body. Fibers are wound around the roller. The top of the box body has an end cap that seals the box body. The end cap and the box body are sealed together by a sealing ring. The box body has an opening for the fiber to pass through, and a conduit is located at the opening.

6. The thermosetting resin-based composite material 3D printing device according to claim 1, characterized in that: The resin feeding unit includes a barrel, with a pressure source at the top of the barrel for feeding the resin into the manifold, and the bottom outlet of the barrel connected to the resin inlet of the manifold. The barrel is located on one side of the manifold.

7. The thermosetting resin-based composite material 3D printing device according to claim 1, characterized in that: The fixing frame includes a fixing plate, one side of which is provided with a first fixing ring and a second fixing ring for fixing the resin feeding unit, and the other side of which is provided with a fixing seat for fixing the fiber feeding unit.

8. A printing method using the thermosetting resin-based composite material 3D printing apparatus according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Load the thermosetting resin material into the barrel, load the continuous fiber into the box, and cover the end. Pull the fiber from the box to the guide tube, and lead it out through the manifold and the print head. S2. Start the coolant circulation device, and the coolant will cool the print head through the condenser tube; Turn on the ceramic heating element to bring it to the resin curing temperature of 200℃-400℃; S3. Start the pressure source. The pressure source sends the thermosetting resin in the barrel into the manifold. The thermosetting resin and fiber are mixed in the manifold and enter the print head together. They are impregnated and coated in the print head. The condenser cools the thermosetting resin to maintain its fluidity and improve the impregnation effect. The thermosetting resin and fiber in the print head are extruded from the nozzle and deposited on the printing platform. S4. The printhead moves on the printing platform, and the ceramic heating element heats and cures the thermosetting resin on the printing platform in situ, thus shaping the composite material.

9. A printing method according to claim 8, characterized in that: In S1, the thermosetting resin material comprises the following components in parts by weight: 100 parts thermosetting resin, 5-15 parts latent curing agent, and 1-10 parts rheology modifier; the thermosetting resin is one of epoxy resin, unsaturated polyester, cyanate ester resin, methacrylate, and dicyclopentadiene resin; the latent curing agent is one of imidazole, amine, dicyandiamide, ionic liquid, benzoyl peroxide, and azobisisobutyronitrile; the rheology modifier is one of nano clay and nano silica; the fiber is one of carbon fiber, glass fiber, Kevlar fiber, ceramic fiber, and natural plant fiber; and the fiber bundle is 1K, 3K, 6K, or 12K.

10. A printing method according to claim 8, characterized in that: In step S2, the condenser maintains the temperature of the thermosetting resin inside the printhead at 20℃-80℃; in step S4, the printing movement speed of the printhead is 25. -150 The printing spacing is 0.8-1.2 times the nozzle diameter, and the layer thickness is 0.5-1.1 times the nozzle diameter.

Images