One-step forming device and method for continuous fiber renewable composite material

Abstract

The present invention relates to a one-step forming device for a continuous fiber renewable composite material, comprising: a free motion system, a plasticizing extrusion unit and a continuous wire feeding unit, wherein the plasticizing extrusion unit is connected to the free motion system, and the free motion system drives the plasticizing extrusion unit to realize movement in space, and the continuous wire feeding unit is used to feed plant fibers into the plasticizing extrusion unit. The one-step forming device for a continuous fiber renewable composite material of the present invention melts thermoplastic plastics by plasticizing extrusion of a screw, and uses a roller device to transport continuous plant fibers to the inside of a die cavity, and uses the movement of the melt in the cavity to impregnate the continuous plant fibers, and at the same time, the plant fibers and the melt are continuously extruded from a nozzle under pressure, and the petal-shaped structure design of the plant fiber guide tube increases the interaction time and the wetting area between the continuous plant fibers and the plastic melt, which is beneficial to improving the interface bonding between the two.

Description

Technical Field

[0001] The invention relates to the technical field of biodegradable composite material molding, and in particular to a one-step molding device and method for a continuous fiber renewable composite material. Background Art

[0002] Continuous plant fiber reinforced thermoplastic molding composites have excellent mechanical properties due to the continuity of plant fibers, and have broad application prospects in the fields of aerospace, automobile rails, etc. Compression molding, in-situ polymerization thermoplastic resin transfer molding and automatic placement molding technology are currently the main molding processes for continuous plant fiber reinforced thermoplastic molding composites.

[0003] Compression molding is to place thermoplastics and continuous plant fibers into a mold cavity, melt the thermoplastics through external pressure and heating, thereby impregnating the plant fibers, and then obtain a composite material through cooling; however, this method has disadvantages such as poor precision and difficulty in forming complex parts.

[0004] The in-situ polymerization thermoplastic resin transfer molding process utilizes the low viscosity of polymer monomers and oligomer systems to impregnate plant fibers to achieve the preparation of high-performance materials. However, this method is currently mainly limited to casting nylon and polymers replaced with oligomers, and is difficult to apply to high-performance thermoplastics; the reaction environment is very sensitive to moisture and oxygen, and has high requirements for the reaction environment; the low monomer conversion rate within a short molding cycle will result in a large amount of oligomers and monomers in the composite material, reducing product performance.

[0005] The automatic placement technology uses a heat source to heat the composite prepreg to melt the plastic matrix and form the product. However, this method relies on the preparation of the prepreg. At the same time, due to the uneven interaction between the heat source and the composite material during the molding process, defects such as scorching and holes occur, resulting in poor product molding accuracy. Secondly, the two-step molding method of prepreg and placement involves many molding process parameters, and the molding process is difficult to control.

[0006] Therefore, there is an urgent need to develop efficient forming methods for continuous plant fiber reinforced thermoplastic molding composites. Summary of the invention

[0007] To this end, the technical problem to be solved by the present invention is to overcome the problem that the molding technology of continuous plant fiber reinforced thermoplastic plastic molding composite materials in the prior art has certain defects and needs to improve the molding technology.

[0008] In order to solve the above technical problems, the present invention provides a one-step forming device for a continuous fiber renewable composite material, comprising: a free motion system, a plasticizing extrusion unit and a continuous wire feeding unit, wherein the plasticizing extrusion unit is connected to the free motion system, and the free motion system drives the plasticizing extrusion unit to move in space, and the continuous wire feeding unit is used to feed plant fibers into the plasticizing extrusion unit; the plasticizing extrusion unit comprises a motor, a fixed support frame, a spiral conveying device, a fiber wire tube, a heating block and a feeding port, wherein the motor and the spiral conveying device are both arranged on the fixed support frame, and the motor and the spiral conveying device are connected, and the motor serves as a driving source for the spiral conveying device, the heating block is connected to the spiral conveying device, the feeding port is arranged on the spiral conveying device, and the feeding port is used to feed materials into the spiral conveying device, the fiber wire tube is arranged between the head of the spiral conveying device and the continuous wire feeding unit, the fiber wire tube is used to introduce the plant fibers in the continuous wire feeding unit into the head of the spiral conveying device, and the plasticized molten plastic in the head of the spiral conveying device and the plant fibers introduced by the fiber wire tube are uniformly extruded. The one-step forming device for continuous fiber renewable composite materials of the present invention melts thermoplastic plastics through plasticizing extrusion of a screw, transports continuous plant fibers to the interior of a die cavity using a roller device, impregnates the continuous plant fibers using the movement of the melt in the cavity, and simultaneously, the plant fibers and the melt are continuously extruded from a nozzle under pressure.

[0009] In one embodiment of the present invention, the fiber wire conduit includes an annular conduit and a plurality of petal bodies, one end of the plurality of petal bodies is connected to the annular conduit, the annular conduit is arranged on a spiral conveying device, the plurality of petal bodies are located in the head of the spiral conveying device, and the other end of the plurality of petal bodies extends out of the head of the spiral conveying device, and the center of the annular conduit is a cavity for plant fibers to pass through.

[0010] In one embodiment of the present invention, the plurality of petal bodies are arranged in a circular array with the center line of the annular conduit as the center, and separation gaps are provided between the plurality of petal bodies, and the central area between the plurality of petal bodies is cavity 2 for plant fibers to pass through.

[0011] In one embodiment of the present invention, the screw conveying device includes a barrel, a screw rod and a head, the screw rod is arranged in the barrel, and the screw rod is connected to the motor, the head is arranged at the head position of the barrel, and the annular conduit passes through the side wall of the head.

[0012] In one embodiment of the present invention, a discharge port is provided inside the machine head, and the discharge port is arranged in a conical shape, and one end of the plurality of petal bodies away from the annular guide tube passes through the discharge port.

[0013] In one embodiment of the present invention, the angle between the annular conduit and the radial section through which the nose is located ranges from 30 to 75 degrees.

[0014] In one embodiment of the present invention, the continuous wire feeding unit includes a seat frame, a tensioning spring, a roller device, a servo motor and bolts. The seat frame is connected to a spiral conveying device through bolts. A fiber roll is provided on the seat frame. The roller device and the servo motor are both arranged on the seat frame. The plant fibers on the fiber roll enter the fiber wire tube through the guidance of the roller device. The tensioning spring is used to provide tensioning force to the roller device.

[0015] In one embodiment of the present invention, a position-limiting guide entry tube is provided on the seat frame, and the plant fibers on the fiber roll pass through the position-limiting guide entry tube.

[0016] In one embodiment of the present invention, the roller device includes a main guide wheel and an auxiliary guide wheel, the plant fiber passes through the main guide wheel and the auxiliary guide wheel, and the tension spring is connected to the main guide wheel to keep the main guide wheel tensioning the plant fiber.

[0017] A method for a one-step molding device of a continuous fiber renewable composite material comprises the following steps:

[0018] S1. Connect the equipment to the free motion system through fixed support, and the free motion system provides the motion trajectory of the product;

[0019] S2, passing the plant fiber between the main guide wheel and the auxiliary guide wheel of the continuous wire feeding unit, and the plant fiber is introduced between the plurality of petal bodies through the annular guide tube;

[0020] S3, heating the screw conveying device by a heating block to make the screw conveying device reach the working temperature;

[0021] S4, start the motor to drive the screw rod in the screw conveying device to rotate at a certain speed;

[0022] S5, adding thermoplastic plastic into the screw conveyor through the feeding port, and the completely plasticized molten plastic flows through the separation gaps between the petal bodies in the die cavity of the die head to achieve local pre-infiltration of the continuous plant fibers, and finally the plant fibers and the plasticized molten plastic are continuously and evenly extruded through the die head;

[0023] S6, adjusting the rotation speed of the servo motor and the pressure of the tension spring to ensure that the plastic melt forms a uniform and continuous wrapping around the continuous plant fibers;

[0024] S7. The continuously extruded continuous plant fiber-filled thermoplastic composite is deposited layer by layer on the molding area of ​​the workbench to form a target sample.

[0025] The above technical solution of the present invention has the following advantages compared with the prior art:

[0026] The one-step molding device and method of continuous fiber renewable composite materials described in the present invention, continuous plant fiber reinforced thermoplastic plastic matrix, improves the problem of unstable product performance caused by uneven distribution of short plant fibers, and reduces the probability of nozzle clogging during printing. The orderly arrangement and orientation of the continuous plant fibers in the plastic matrix are beneficial to further improving the performance of the composite material; the continuous plant fibers are combined with additive manufacturing technology to achieve one-time molding of composite parts, reducing the two processes of preparing prepregs and molding of traditional composite materials, saving molding time, improving efficiency and reducing costs; the continuous plant fibers have a short heating time in the mold cavity, avoiding the decomposition of natural plant fibers (such as bamboo plant fibers) during the molding process, expanding the types of plant fibers, and realizing the molding of fully degradable continuous plant fiber reinforced composite materials; the petal-shaped structure design of the plant fiber guide tube increases the interaction time and wetting area between the continuous plant fibers and the plastic melt, which is beneficial to improving the interface bonding between the two. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein

[0028] Figure 1 It is a schematic diagram of the overall structure of the one-step molding device of the continuous fiber renewable composite material of the present invention;

[0029] Figure 2 It is a structural schematic diagram of the plasticizing extrusion unit of the present invention;

[0030] Figure 3 The present invention Figure 2 A partial enlarged view of the middle A;

[0031] Figure 4 is a schematic structural diagram of the fiber conductor tube of the present invention;

[0032] Figure 5 is a cross-sectional view of a fiber conduit of the present invention;

[0033] Figure 6 It is a structural schematic diagram of a continuous wire feeding unit of the present invention;

[0034] Figure 7 This is a physical picture of the composite material prepared from the continuous bamboo fiber reinforced polyethylene of the present invention;

[0035] Figure 8 It is a tensile stress-strain comparison curve diagram of the one-step formed pure polyethylene material and the bamboo fiber reinforced polyethylene composite material of the present invention.

[0036] Explanation of the markings in the drawings in the specification: free motion system 1, plasticizing extrusion unit 2, motor 21, fixed support frame 22, screw conveying device 23, barrel 231, screw rod 232, head 233, discharge port 2331, fiber wire tube 24, annular duct 241, petal body 242, cavity one 243, separation gap 244, cavity two 245, heating block 25, feeding port 26, continuous wire feeding unit 3, seat frame 31, limit guide entry tube 311, tensioning spring 32, roller device 33, main guide wheel 331, auxiliary guide wheel 332, servo motor 34, bolt 35. DETAILED DESCRIPTION

[0037] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0038] Reference Figure 1 As shown, the one-step forming device of continuous fiber renewable composite material of the present invention comprises: a free motion system 1, a plasticizing extrusion unit 2 and a continuous wire feeding unit 3, wherein the plasticizing extrusion unit 2 is connected to the free motion system 1, and the free motion system 1 drives the plasticizing extrusion unit 2 to realize movement in space, and the continuous wire feeding unit 3 is used to feed plant fiber into the plasticizing extrusion unit 2; it mainly comprises three main parts: the free motion system 1, the plasticizing extrusion unit 2 and the continuous wire feeding unit 3, wherein the thermoplastic material is melted after the plasticizing extrusion unit 2, and the continuous plant fiber is uniformly and stably extruded, and the whole machine completes continuous motion under the clamping of the free motion system 1, and the sample is formed by accumulating layer by layer. Continuous plant fibers include bamboo fibers, flax fibers, ramie fibers, etc. The thermoplastic matrix can be in the form of wire, particles, powder, etc., and the thermoplastic plastic matrix can be pure thermoplastic plastic or thermoplastic plastic composite material. The thermoplastic plastic composite material includes nano-reinforced thermoplastic composite material, short plant fiber reinforced thermoplastic composite material, long plant fiber reinforced thermoplastic composite material and their composite.

[0039] Reference Figure 2As shown, the plasticizing extrusion unit 2 includes a motor 21, a fixed support frame 22, a screw conveying device 23, a fiber wire tube 24, a heating block 25 and a feeding port 26. The motor 21 and the screw conveying device 23 are both arranged on the fixed support frame 22, and the motor 21 and the screw conveying device 23 are connected, and the motor 21 serves as a driving source for the screw conveying device 23. The heating block 25 is connected to the screw conveying device 23. The feeding port 26 is arranged on the screw conveying device 23, and the feeding port 26 is used to feed material into the screw conveying device 23. The fiber wire tube 24 is arranged between the head of the screw conveying device 23 and the continuous wire feeding unit 3. The fiber wire tube 24 is used to introduce the plant fiber in the continuous wire feeding unit 3 into the head of the screw conveying device 23. The plasticized molten plastic in the head of the screw conveying device 23 and the plant fiber introduced by the fiber wire tube 24 are uniformly extruded. The main implementation device of the plasticizing extrusion unit 2 process is composed of a motor 21, a fixed support frame 22, a screw conveyor 23, a heating block 25 and a feeding port 26; in order to realize the manufacturing of complex shapes, the whole set of devices is connected to a manipulator or a motor guide motion device through the fixed support frame 22, so as to realize the movement in space. The heating temperature range of the heating block 25 is: 100~450℃. The speed range of the motor 21 is 1000rpm~3000rpm.

[0040] Reference Figure 4 , 5 As shown, the fiber conductor tube 24 includes an annular conduit 241 and a plurality of petal bodies 242, one end of the plurality of petal bodies 242 is connected to the annular conduit 241, the annular conduit 241 is arranged on the spiral conveying device 23, the plurality of petal bodies 242 are located in the head of the spiral conveying device 23, and the other end of the plurality of petal bodies 242 extends out of the head of the spiral conveying device 23, and the center of the annular conduit 241 is a cavity 1 243 for the plant fiber to pass through. The plurality of petal bodies 242 are arranged in an annular array with the center line of the annular conduit 241 as the center of the circle, and a separation gap 244 is provided between the plurality of petal bodies 242, and the central area between the plurality of petal bodies 242 is a cavity 2 245 for the plant fiber to pass through. The petal body 242 has a conical thread structure, and the direction of rotation of the thread of the petal body 242 is consistent with the rotation direction of the screw rod on the screw conveying device 23. The angle is 30°~50°, and the pitch is 20~30. The relevant values ​​are adjusted according to the internal space of the head of the screw conveying device 23.

[0041] Reference Figure 3As shown, the screw conveying device 23 includes a barrel 231, a screw rod 232 and a head 233. The screw rod 232 is arranged in the barrel 231 and connected to the motor 21. The head 233 is arranged at the head position of the barrel 231, and the annular guide tube 241 passes through the side wall of the head 233. A discharge port 2331 is arranged inside the head 233. The discharge port 2331 is arranged in a conical shape, and one end of the plurality of petal bodies 242 away from the annular guide tube 241 passes through the discharge port 2331. The angle range between the annular guide tube 241 and the radial section where the head 233 is located is: 30 to 75 degrees. The rotation speed range of the screw rod 232 is 30rpm to 60rpm.

[0042] Reference Figure 6 As shown, the continuous wire feeding unit 3 includes a seat frame 31, a tensioning spring 32, a roller device 33, a servo motor 34 and a bolt 35. The seat frame 31 is connected to the spiral conveying device 23 through the bolt 35. The seat frame 31 is provided with a fiber roll. The roller device 33 and the servo motor 34 are both arranged on the seat frame 31. The plant fibers on the fiber roll enter the fiber wire tube 24 through the guidance of the roller device 33. The tensioning spring 32 is used to provide the tensioning force of the roller device 33. The seat frame 31 is provided with a limited guide entry tube 311, and the plant fibers on the fiber roll pass through the limited guide entry tube 311. The roller device 33 includes a main guide wheel 331 and an auxiliary guide wheel 332. The plant fibers pass through the main guide wheel 331 and the auxiliary guide wheel 332. The tensioning spring 32 is connected to the main guide wheel 331 to keep the main guide wheel 331 tensioning the plant fibers. The plant fiber conveying speed of the continuous wire feeding unit 3 is: 40-80 mm / s.

[0043] The one-step forming device of continuous fiber renewable composite material of the present invention mainly includes three links: free movement in space, plasticizing extrusion, and continuous wire feeding. The main implementation device of plasticizing extrusion is composed of a motor, a fixed support, a screw conveying device, a heating block, a fixed hole and a feeding device. The screw conveying device is composed of a screw rod, a barrel, a plant fiber guide tube and a machine head. The main implementation device of continuous wire feeding is composed of a seat frame, a tensioning spring and a roller device, a servo motor, and bolts. In order to realize the manufacturing of complex shapes and to ensure that the extrusion of materials and the transmission of plant fibers are carried out synchronously during the additive processing, the seat frame of continuous wire feeding and the fixed hole of plasticizing extrusion are connected as a whole. The whole set of equipment is connected to the manipulator or the motor guide motion device through a fixed support to realize the movement in space.

[0044] Based on the above structure, a method for a one-step molding device of a continuous fiber renewable composite material comprises the following steps:

[0045] S1, connecting the device to the free motion system 1 through the fixed support 22, and the free motion system 1 provides the motion trajectory of the product forming;

[0046] S2, passing the plant fiber between the main guide wheel 331 and the auxiliary guide wheel 332 of the continuous wire feeding unit 3, and the plant fiber is introduced into between the plurality of petal bodies 242 through the annular guide tube 241;

[0047] S3, heating the screw conveying device 23 by the heating block 25, so that the screw conveying device 23 reaches the working temperature;

[0048] S4, starting the motor 21 to drive the screw rod 232 in the screw conveying device 23 to rotate at a constant speed;

[0049] S5, adding thermoplastic plastic into the screw conveyor 23 through the feed port 26, the completely plasticized molten plastic flows through the separation gaps 244 between the plurality of petal bodies 242 in the mold cavity of the die 233, thereby achieving local pre-wetting of the continuous plant fibers, and finally the plant fibers and the plasticized molten plastic are continuously and evenly extruded through the die 233;

[0050] S6, adjusting the rotation speed of the servo motor 34 and the pressure of the tension spring 32 to ensure that the plastic melt forms a uniform and continuous wrapping around the continuous plant fibers;

[0051] S7. The continuously extruded continuous plant fiber-filled thermoplastic composite is deposited layer by layer on the molding area of ​​the workbench to form a target sample.

[0052] Reference Figure 7 As shown, it is a composite material prepared by continuous bamboo fiber reinforced polyethylene. Figure 8 It is its tensile stress-strain curve. It can be seen that compared with pure polyethylene material, the tensile strength and elastic modulus of the composite material reinforced with bamboo fiber are greatly increased.

[0053] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A one-step molding device for continuous fiber renewable composite materials, characterized in that: include: A free motion system, a plasticizing extrusion unit and a continuous wire feeding unit, wherein the plasticizing extrusion unit is connected to the free motion system, and the free motion system drives the plasticizing extrusion unit to move in space, and the continuous wire feeding unit is used to feed plant fibers into the plasticizing extrusion unit; The plasticizing extrusion unit comprises a motor, a fixed support frame, a screw conveying device, a fiber wire tube, a heating block and a feeding port, wherein the motor and the screw conveying device are both arranged on the fixed support frame, and the motor and the screw conveying device are connected, and the motor serves as a driving source for the screw conveying device, the heating block and the screw conveying device are connected, the feeding port is arranged on the screw conveying device, and the feeding port is used to feed materials into the screw conveying device, the fiber wire tube is arranged between the head of the screw conveying device and the continuous wire feeding unit, and the fiber wire tube is used to introduce the plant fibers in the continuous wire feeding unit into the head of the screw conveying device, and the plasticized molten plastic in the head of the screw conveying device and the plant fibers introduced by the fiber wire tube are uniformly extruded; The fiber wire conduit includes an annular conduit and a plurality of petal bodies, one end of the plurality of petal bodies is connected to the annular conduit, the annular conduit is arranged on a spiral conveying device, the plurality of petal bodies are located in the head of the spiral conveying device, and the other end of the plurality of petal bodies extends out of the head of the spiral conveying device, and the center of the annular conduit is a cavity for plant fibers to pass through.

2. The one-step forming device for continuous fiber renewable composite material according to claim 1, characterized in that: The plurality of petal bodies are arranged in a circular array with the center line of the circular conduit as the center, and separation gaps are provided between the plurality of petal bodies. The central area between the plurality of petal bodies is a second cavity for plant fibers to pass through.

3. The one-step forming device for continuous fiber renewable composite material according to claim 1, characterized in that: The screw conveying device comprises a barrel, a screw rod and a head. The screw rod is arranged in the barrel and connected to a motor. The head is arranged at the head position of the barrel, and the annular conduit penetrates the side wall of the head.

4. The one-step forming device for continuous fiber renewable composite material according to claim 3, characterized in that: A discharge port is arranged inside the machine head, and the discharge port is arranged in a cone shape, and one end of the plurality of petal bodies away from the annular guide tube passes through the discharge port.

5. The one-step forming device for continuous fiber renewable composite material according to claim 3, characterized in that: The angle between the annular conduit and the radial section through which the handpiece is located ranges from 30 to 75 degrees.

6. The one-step forming device for continuous fiber renewable composite material according to claim 1, characterized in that: The continuous wire feeding unit includes a seat frame, a tensioning spring, a roller device, a servo motor and bolts. The seat frame is connected to a spiral conveying device through bolts. A fiber roll is provided on the seat frame. The roller device and the servo motor are both arranged on the seat frame. The plant fibers on the fiber roll enter the fiber wire tube through the guidance of the roller device. The tensioning spring is used to provide tensioning force for the roller device.

7. The one-step forming device for continuous fiber renewable composite material according to claim 6, characterized in that: The seat frame is provided with a position-limiting guide entry tube, and the plant fibers on the fiber roll pass through the position-limiting guide entry tube.

8. The one-step forming device for continuous fiber renewable composite material according to claim 7, characterized in that: The roller device comprises a main guide wheel and an auxiliary guide wheel, the plant fiber passes through the main guide wheel and the auxiliary guide wheel, and the tension spring is connected to the main guide wheel to keep the main guide wheel tensioning the plant fiber.

9. The method of the one-step forming device of continuous fiber renewable composite material according to claim 1, characterized in that: The steps include: S1. Connect the equipment to the free motion system through fixed support, and the free motion system provides the motion trajectory of the product; S2, passing the plant fiber between the main guide wheel and the auxiliary guide wheel of the continuous wire feeding unit, and the plant fiber is introduced between the plurality of petal bodies through the annular guide tube; S3, heating the screw conveying device by a heating block to make the screw conveying device reach the working temperature; S4, start the motor to drive the screw rod in the screw conveying device to rotate at a certain speed; S5, adding thermoplastic plastic into the screw conveyor through the feeding port, and the completely plasticized molten plastic flows through the separation gaps between the petal bodies in the die cavity of the die head to achieve local pre-infiltration of the continuous plant fibers, and finally the plant fibers and the plasticized molten plastic are continuously and evenly extruded through the die head; S6, adjusting the rotation speed of the servo motor and the pressure of the tension spring to ensure that the plastic melt forms a uniform and continuous wrapping around the continuous plant fibers; S7. The continuously extruded continuous plant fiber-filled thermoplastic composite is deposited layer by layer on the molding area of ​​the workbench to form a target sample.

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