A fiber-reinforced composite additive manufacturing actuator with real-time external temperature and pressure control

Abstract

The present invention belongs to the technical field of additive manufacturing of fiber-reinforced composite materials, and proposes an actuator for additive manufacturing of fiber-reinforced composite materials with real-time external temperature and pressure control. The actuator increases the surface temperature of the composite material laid on the printing platform through an external auxiliary heating unit, thereby reducing the viscosity of its resin and facilitating bonding with the next layer; the roller-assisted extrusion unit applies extrusion force to the newly laid layer to enhance the interlayer bonding effect; the feedback control unit processes the collected distance between the laser end and the printing layer and the extrusion force signal of the extrusion roller on the printing layer, and drives the single-axis robot to perform feedback adjustment so that the distance and extrusion force are reasonable values. The present invention improves the problem of weak interlayer bonding strength of components in the process of additive manufacturing of fiber-reinforced composite materials, and realizes the improvement of interlayer bonding strength of components through external auxiliary laser heating and roller extrusion, and real-time feedback control.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber-reinforced composite material additive manufacturing, and in particular to a fiber-reinforced composite material additive manufacturing actuator with real-time regulation of external temperature and pressure. Background Art

[0002] Additive manufacturing, a quintessential technology of the Third Industrial Revolution, offers high manufacturing precision, minimal material waste, and ease of intelligent and digital processing. Furthermore, it offers a high degree of design freedom, enabling rapid prototyping of components and the creation of complex parts that are difficult to form using traditional machining methods.

[0003] Fiber-reinforced composites, due to their high specific strength and high specific modulus, are increasingly in demand in the aviation, shipbuilding, automotive, and other manufacturing fields. Therefore, combining additive manufacturing technology with fiber-reinforced composites has great application prospects.

[0004] The additive manufacturing of fiber-reinforced composite materials is to heat and melt the forming material, and then stack it layer by layer on the printing platform. Because the bonding strength in the stacking direction cannot be guaranteed, the bonding strength between the component layers is weak, and phenomena such as interlayer peeling are prone to occur during its use. Some scholars have conducted research on this issue. The invention patent number of Wang Hong et al. is CN 110789118A, and the invention name is "A 3D Printer". It invented a printer whose printing platform can move arbitrarily in three dimensions in space. It plans the printing path to be an approximate conical surface, and then performs carbon fiber woven topology optimization on the printed component structure to improve the interlayer bonding strength of the component. However, because the invention mainly focuses on improving the printing path to improve the interlayer bonding quality, the path planning is difficult, the printer design structure is complex, and it is difficult to use. In addition, it does not take into account that the external temperature and pressure during the printing process also have a great impact on the interlayer bonding quality of the component. For example, in the article "Impregnation and interlayer bonding behaviors of 3D-printed continuous carbon-fiber-reinforced poly-ether-ether-ketone composites" published in Composites Part A, Issue 121, 2019, pp. 130-138, Luo Meng et al. used a laser to preheat the interlayers of printed carbon fiber tows and polyetheretherketone composites. However, this method ignored the effect of auxiliary pressure on the printed layers on the interlayer bonding quality of the component. Simply providing auxiliary heating has limited effect on improving the interlayer bonding strength of the component. Therefore, it is necessary to comprehensively consider the effects of external temperature and pressure on interlayer bonding strength during the additive manufacturing process of fiber-reinforced composites to achieve the goal of improving the interlayer bonding quality of the component. However, there is currently no device that can effectively control these parameters simultaneously. Summary of the Invention

[0005] The present invention aims to address current challenges by developing an actuator for additive manufacturing of fiber-reinforced composite materials with real-time external temperature and pressure control. This actuator comprehensively considers the temperature and pressure between printed layers during the additive manufacturing process. It adjusts these parameters in real time through external laser heating and roller extrusion, maintaining them at optimal values through feedback control, thereby improving the interlayer bonding quality of the formed component.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A fiber-reinforced composite additive manufacturing actuator with real-time external temperature and pressure control, comprising a wire placement unit, an external auxiliary heating unit, a roller-assisted extrusion unit, and a feedback control unit;

[0008] An external auxiliary heating unit raises the temperature of the surface layer of the composite material placed on the printing platform, reducing the viscosity of the resin in the composite material surface layer, making it easier to bond with the next layer. A roller-assisted extrusion unit applies a certain amount of extrusion pressure to the newly placed printing layer to enhance the interlayer bonding effect. During the printing process, a distance sensor and a pressure sensor respectively measure the distance between the laser end and the printing layer and the extrusion pressure of the extrusion roller on the printing layer in real time. A feedback control unit collects the distance and extrusion pressure signals and drives the single-axis robot for feedback adjustment to control the distance and extrusion pressure to reasonable values.

[0009] The wire placement unit is modular and replaceable as needed, expanding the actuator's application range. It includes a wire feed wheel A1, a heating chamber A2, and a printing nozzle A3. Wire is wound around the wire feed wheel A1 and driven into the heating chamber A2 by the wire feed wheel A1. The heating chamber A2 is connected to the printing nozzle A3. After the wire is melted in the heating chamber A2, it is placed onto the printing platform through the printing nozzle A3, achieving automated wire placement.

[0010] The external auxiliary heating unit is fixed to the base plate and is located on one side of the wire placement unit; the external auxiliary heating unit includes a heating device B1, a clamping mechanism B2, a single-degree-of-freedom turntable aB3 and a single-axis robot aB4; the clamping mechanism B2 is a special clamp, and the heating device B1 is fixed to the single-degree-of-freedom turntable aB3 through the clamping mechanism B2, and the single-degree-of-freedom turntable aB3 is connected to the single-axis robot aB4; the rotation of the single-degree-of-freedom turntable aB3 is controlled to control the distance between the heating point of the heating device B1 on the printing layer and the printing nozzle A3; the position of the heating device B1 on the single-axis robot aB4 is adjusted to control the distance between the heating device B1 and the printing layer; the power of the heating device B1 is adjusted to change the heating temperature value of the composite material layer surface, so as to reduce the viscosity of the resin in the laid layer and facilitate bonding with the next printing layer;

[0011] The roller-assisted extrusion unit is fixed to the base plate and located on the other side of the wire placement unit. The roller-assisted extrusion unit includes a pressure device C1, an extrusion rod C2, an adapter plate C3, a single-degree-of-freedom turntable bC4, and a single-axis robot bC5, which are connected in sequence. The rotation of the single-degree-of-freedom turntable bC4 controls the distance between the pressure device C1 and the print nozzle A3 on the printed layer, thereby controlling the relative position of the extrusion point and the print nozzle A3. The telescopic length of the extrusion rod C2 and its position on the single-axis robot bC5 control the distance between the pressure device C1 and the printed layer, thereby adjusting the extrusion force and improving the interlayer bonding effect of the printed component.

[0012] The feedback control unit includes a pressure sensor D1, a distance sensor D2, a transmitter D3 and a controller D4; the pressure sensor D1 is installed on the extrusion rod C2, and measures the extrusion force between the pressure device C1 and the printed layer in real time. The auxiliary pressure required to be applied by the pressure device C1 is the appropriate interlayer pressure during the component printing process; the distance sensor D2 is installed at the end of the heating device B1, and measures the distance between the end of the heating device B1 and the printed layer in real time; the pressure sensor D1 and the distance sensor D2 are connected to the transmitter D3 to transmit signals; the transmitter D3 is connected to the controller D4; the signal is processed by the transmitter D3 and input into the controller D4 for feedback control to ensure that the distance between the end of the heating device B1 and the printed layer and the extrusion force of the pressure device C1 on the printed layer are given values.

[0013] The external auxiliary heating unit and the roller-assisted extrusion unit are set to have a mass of less than 3 kg and a vertical inclination θ1 of the heating device B1 less than 70° based on the load requirements of the base plate and the characteristics of the fiber-reinforced composite material; the mass of the roller-assisted extrusion unit is less than 2.5 kg, and the vertical inclination θ2 of the extrusion rod C2 is less than 60°; the vertical inclination θ1 of the heating device B1 and the vertical inclination θ2 of the extrusion rod C2 satisfy θ1=(1.1-1.3)θ2, and the positions of the heating device B1 and the extrusion rod C2 are linked.

[0014] The external auxiliary heating unit and the roller-assisted pressure unit are modular and detachable; the external heat source of the central heating device B1 of the external auxiliary heating unit is plasma, ultrasound, laser or infrared; the temperature range of the heating point is 80-150°C; the power source of the roller-assisted extrusion unit is an electric slide rail or air pressure; the pressure device C1 of the roller-assisted extrusion unit is an extrusion roller.

[0015] When the external heat source is laser, the laser power is 5-50W and the wavelength is 500-800nm.

[0016] The extrusion rod C2 is a retractable electric extrusion rod with a diameter of 0.3-0.5 times the width of the pressure device C1; the extrusion roller is an outward-convex polyurethane-coated round roller with a width of 6 times the diameter of the printed wire and a shoulder width of 3 times the diameter of the printed wire. The extrusion roller rotates 360 degrees along the axis of the extrusion rod C2, and the extrusion force is within the range of 3-18N.

[0017] The end of the printing nozzle A3, the heating point of the heating device B1 and the end of the pressurizing device C1 are on the same plane; the diameter of the heating point of the heating device B1 is larger than the width of a single path of the laid wire, and the distance L1 between the printing nozzle A3 and the pressurizing device C1 and the distance L2 between the printing nozzle A3 and the heating point of the heating device B1 satisfy the expression: L2≤0.8L1.

[0018] The structure of the wire laying unit varies according to the printing method; when the printing method is pre-impregnation printing, the wire laying unit is a pre-impregnation wire laying unit, which is a single wire channel unit; a wire feeding channel is provided above the heating chamber A2, and one of the continuous fiber reinforced pre-impregnated composite wire X1 or the short fiber reinforced pre-impregnated composite wire X2 is used as the raw material, which is heated, melted and extruded and laid after passing through the channel to realize 3D printing of composite material components; when the printing method is in-situ impregnation printing, the wire laying unit is an in-situ impregnation wire laying unit, which is a double wire channel unit; there are two wire feeding channels above and on the side of the heating chamber A2 respectively, and the resin wire X3 and the continuous fiber wire X4 are used as raw materials. The resin wire X3 passes through the side channel, and the continuous fiber wire X4 passes through the upper channel, and then is heated, melted and extruded and laid to realize 3D printing of composite material components.

[0019] The external auxiliary heating unit and the roller auxiliary extrusion unit are adjusted in real time.

[0020] A fiber-reinforced composite additive manufacturing actuator with real-time external temperature and pressure regulation can realize the automated placement of wires, intelligent regulation of external auxiliary heating temperature, and adaptive sensing of extrusion force during the fiber-reinforced composite additive manufacturing process. The three work together in synergy during fiber-reinforced composite additive manufacturing.

[0021] The beneficial effects of the present invention are as follows: the problem of weak interlayer bonding strength of components in the additive manufacturing process of fiber-reinforced composite materials is improved. The existing technology does not simultaneously consider the influence of external temperature and pressure on the interlayer bonding effect of printed components during the printing process. The present invention comprehensively considers the relationship between the two in improving the interlayer bonding strength of components, and improves the interlayer bonding performance of printed components through the synergistic effect of external auxiliary laser heating and roller extrusion. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the overall structure of a fiber-reinforced composite material additive manufacturing actuator with real-time external temperature and pressure control according to the present invention, which is suitable for pre-impregnated composite materials;

[0023] Figure 2 This is a schematic diagram of the overall structure of a fiber-reinforced composite additive manufacturing actuator with real-time regulation of external temperature and pressure according to the present invention, which is suitable for resin wires and continuous fiber wires.

[0024] Among them: A1-wire feeding wheel, A2-heating chamber, A3-printing nozzle, B1-heating device, B2-clamping mechanism, B3-single-degree-of-freedom turntable a, B4-single-axis robot a, C1-pressurizing device, C2-extrusion rod, C3-adapter plate, C4-single-degree-of-freedom turntable b, C5-single-axis robot b, D1-pressure sensor, D2-distance sensor, D3-transmitter, D4-controller, X1-continuous fiber reinforced pre-impregnated composite wire, X2-short fiber reinforced resin-based composite wire, X3-resin wire, X4-continuous fiber wire. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be noted that the examples and descriptions in the present invention are only used to explain the invention and are not intended to limit the invention in any way.

[0026] Example 1

[0027] This specific example uses the printing of continuous fiber-reinforced pre-impregnated composite materials as an example. 1K continuous carbon fiber filaments reinforced with PA pre-impregnated filaments are used as the raw material for additive manufacturing of fiber-reinforced composite materials. The target component is a 50mm × 50mm × 20mm rectangular parallelepiped structure. Based on the material properties and structural characteristics, appropriate process parameters were selected for this example: nozzle temperature of 210°C, interlayer thickness of 0.4mm, and printing speed of 6mm / s.

[0028] The fiber-reinforced composite material additive manufacturing actuator with real-time external temperature and pressure control includes a wire placement unit, an external auxiliary heating unit, a roller-assisted extrusion unit and a feedback control unit;

[0029] The wire placement unit includes a wire feed wheel A1, a heating chamber A2, and a printing nozzle A3. The wire enters the heating chamber A2 under the action of the wire feed wheel A1, melts therein, and is placed onto the printing platform through the printing nozzle A3.

[0030] A pre-impregnated wire placement unit, also known as a single-wire channel unit, is used. A wire inlet channel is located above the nozzle. 1K continuous carbon fiber-reinforced PA pre-impregnated wire is used as the raw material. It is inserted through the channel above the pre-impregnated wire placement unit, then heated, melted, and extruded for placement, enabling additive manufacturing of composite components.

[0031] The external auxiliary heating unit includes a heating device laser, a clamping mechanism B2, a single-degree-of-freedom turntable aB3, and a single-axis robot aB4. The model of the laser is QBH.25.100, the model of the single-degree-of-freedom turntable aB3 is EHD86-40, and the model of the single-axis robot aB4 is E-EHX21-6030-C-1. The laser is fixed on the single-degree-of-freedom turntable aB3 through the clamping mechanism B2, and the single-degree-of-freedom turntable aB3 is connected to the single-axis robot aB4; the external auxiliary heating unit is fixed on the left side of the wire placement unit; by controlling the rotation of the single-degree-of-freedom turntable aB3, the distance between the laser spot on the printing layer and the printing nozzle A3 can be controlled, thereby controlling the relative position of the heating point and the printing nozzle A3; by adjusting the position of the laser on the single-axis robot aB4, the distance between the laser and the printing layer can be controlled; by adjusting the power of the laser, the heating temperature value of the composite material surface can be changed, so that the viscosity of the resin in the laid layer is reduced, which is convenient for combining with the next printing layer;

[0032] The roller-assisted extrusion unit includes an extrusion roller, an extrusion rod C2, an adapter plate C3, a single-degree-of-freedom turntable bC4, and a single-axis robot bC5. The model of the single-degree-of-freedom turntable bC4 is EHD86-60, and the model of the single-axis robot bC5 is E-EHX21-6030-C-1. The extrusion roller, the extrusion rod C2, the adapter plate C3, the single-degree-of-freedom turntable bC4, and the single-axis robot bC5 are connected in sequence; the roller-assisted extrusion unit is fixed to the right side of the wire placement unit; by controlling the rotation of the single-degree-of-freedom turntable bC4, the distance between the extrusion roller and the printing nozzle A3 on the printing layer can be controlled, and then the relative position of the extrusion point and the printing nozzle A3 can be controlled; by adjusting the position of the extrusion rod C2 on the single-axis robot bC5, the distance between the extrusion roller and the printing layer can be controlled, and then the value of the extrusion force can be adjusted to improve the bonding effect between the layers of the printed components;

[0033] The feedback control unit consists of a pressure sensor D1, a distance sensor D2, a transmitter D3, and a controller D4. The pressure sensor D1 is model SBT641, the distance sensor D2 is model UM12-1172251, the transmitter D3 is model RS232485, and the controller D4 is model SBT951. Pressure sensor D1, mounted on extrusion rod C2, measures the pressure between the extrusion roller and the printed layer in real time. The auxiliary pressure applied by the extrusion roller is the appropriate interlayer pressure during component printing. Distance sensor D2, mounted at the end of the laser, measures the distance between the laser tip and the printed layer in real time. The pressure sensor D1 and distance sensor D2 are connected to transmitter D3, processing their output signals and transmitting them to controller D4. Controller D4 provides feedback control to ensure that the distance between the laser tip and the printed layer and the extrusion roller's pressure on the printed layer remain at given values.

Claims

1. A fiber-reinforced composite material additive manufacturing actuator with real-time external temperature and pressure control, characterized in that: The actuator includes a wire placement unit, an external auxiliary heating unit, a roller-assisted extrusion unit and a feedback control unit; An external auxiliary heating unit raises the temperature of the surface layer of the composite material placed on the printing platform, reducing the viscosity of the resin in the composite material surface layer and allowing it to bond with the next layer. A roller-assisted extrusion unit applies a certain amount of extrusion pressure to the newly placed printed layer to enhance the interlayer bonding effect. During the printing process, a distance sensor and a pressure sensor respectively measure the distance between the laser end and the printed layer and the extrusion pressure of the extrusion roller on the printed layer in real time. A feedback control unit collects the distance and extrusion pressure and drives the single-axis robot for feedback adjustment to control the distance and extrusion pressure to reasonable values. The wire placement unit includes a wire feeding wheel (A1), a heating chamber (A2) and a printing nozzle (A3); a wire is wound on the wire feeding wheel (A1), and the wire is driven into the heating chamber (A2) by the wire feeding wheel (A1); the heating chamber (A2) is connected to the printing nozzle (A3), and the wire is melted in the heating chamber (A2) and then placed on the printing platform through the printing nozzle (A3), thereby realizing automatic wire placement; The external auxiliary heating unit is fixed on the base plate and is located on one side of the wire laying unit; the external auxiliary heating unit includes a heating device (B1), a clamping mechanism (B2), a single-degree-of-freedom turntable a (B3) and a single-axis robot a (B4); the heating device (B1) is fixed on the single-degree-of-freedom turntable a (B3) through the clamping mechanism (B2), and the single-degree-of-freedom turntable a (B3) is connected to the single-axis robot a (B4); the rotation of the single-degree-of-freedom turntable a (B3) is controlled to control the distance between the heating point of the heating device (B1) on the printing layer and the printing nozzle (A3); the position of the heating device (B1) on the single-axis robot a (B4) is adjusted to control the distance between the heating device (B1) and the printing layer; the power of the heating device (B1) is adjusted to change the heating temperature value of the surface of the composite material layer, so that the viscosity of the resin in the laid layer is reduced to facilitate combination with the next printing layer; The roller-assisted extrusion unit is fixed on the base plate and is located on the other side of the wire placement unit; the roller-assisted extrusion unit includes a pressurizing device (C1), an extrusion rod (C2), an adapter plate (C3), a single-degree-of-freedom turntable b (C4), and a single-axis robot b (C5) connected in sequence; the rotation of the single-degree-of-freedom turntable b (C4) is controlled to control the distance between the pressurizing device (C1) and the printing nozzle (A3) on the printing layer, thereby controlling the relative position of the extrusion point and the printing nozzle (A3); the telescopic length of the extrusion rod (C2) and its position on the single-axis robot b (C5) are adjusted to control the distance between the pressurizing device (C1) and the printing layer, thereby adjusting the value of the extrusion force; The feedback control unit includes a pressure sensor (D1), a distance sensor (D2), a transmitter (D3) and a controller (D4); the pressure sensor (D1) is installed on the extrusion rod (C2) to measure the extrusion force between the pressure device (C1) and the printing layer in real time; the distance sensor (D2) is installed at the end of the heating device (B1) to measure the distance between the end of the heating device (B1) and the printing layer in real time; the pressure sensor (D1) and the distance sensor (D2) are connected to the transmitter (D3) to transmit signals; the transmitter (D3) is connected to the controller (D4); the signal is processed by the transmitter (D3) and input into the controller (D4) for feedback control to ensure that the distance between the end of the heating device (B1) and the printing layer and the extrusion force of the pressure device (C1) on the printing layer are given values; The external auxiliary heating unit and the roller auxiliary extrusion unit are set to have a mass of less than 3 kg and a vertical inclination θ1 of the heating device (B1) less than 70° according to the load requirements of the base plate and the characteristics of the fiber reinforced composite material. The mass of the roller auxiliary extrusion unit is less than 2.5 kg, and the vertical inclination θ2 of the extrusion rod (C2) is less than 60°. The vertical inclination θ1 of the heating device (B1) and the vertical inclination θ2 of the extrusion rod (C2) satisfy θ1=(1.1-1.3)θ2, and the positions of the heating device (B1) and the extrusion rod (C2) are linked. The end of the printing nozzle (A3), the heating point of the heating device (B1) and the end of the pressing device (C1) are on the same plane. The diameter of the heating point of the heating device (B1) is greater than the width of a single path of the laid wire, and the distance L1 between the printing nozzle (A3) and the pressing device (C1) and the distance L2 between the printing nozzle (A3) and the heating point of the heating device (B1) satisfy the expression: L2≤0.8L1.

2. The fiber-reinforced composite additive manufacturing actuator with real-time external temperature and pressure control according to claim 1, characterized in that: The external auxiliary heating unit and the roller-assisted pressing unit are modular and detachable; the external heat source of the central heating device (B1) of the external auxiliary heating unit is plasma, ultrasound, laser or infrared; the temperature range of the heating point is 80-150°C; the power source of the roller-assisted extrusion unit is an electric slide rail or air pressure; and the pressurizing device (C1) of the roller-assisted extrusion unit is an extrusion roller.

3. The fiber-reinforced composite additive manufacturing actuator with real-time external temperature and pressure control according to claim 2, characterized in that: The extrusion rod (C2) is a retractable electric extrusion rod with a diameter of 0.3-0.5 times the width of the pressure device (C1); the extrusion roller is an outward-convex polyurethane-coated round roller with a width of 6 times the diameter of the printed wire and a shoulder width of 3 times the diameter of the printed wire. The extrusion roller rotates 360 degrees along the axis of the extrusion rod (C2), and the extrusion force is within the range of 3-18N.

4. The fiber-reinforced composite material additive manufacturing actuator with real-time external temperature and pressure control according to claim 2, characterized in that: When the external heat source is laser, the laser power is 5-50W and the wavelength is 500-800nm.

5. A fiber-reinforced composite material additive manufacturing actuator with real-time external temperature and pressure control according to claim 1 or 2, characterized in that: The structure of the wire placement unit varies depending on the printing method. When the printing method is pre-impregnation printing, the wire placement unit is a pre-impregnation type wire placement unit, which is a single wire channel unit. A wire feeding channel is provided above the heating chamber (A2). One of the continuous fiber reinforced pre-impregnated composite wire (X1) or the short fiber reinforced pre-impregnated composite wire (X2) is used as the raw material. After passing through the channel, it is heated, melted, and extruded and placed to achieve 3D printing of composite material components. When the printing method is in-situ impregnation printing, the wire placement unit is an in-situ impregnation type wire placement unit, which is a double wire channel unit. There are two wire feeding channels above and on the side of the heating chamber (A2), respectively. At the same time, the resin wire (X3) and the continuous fiber wire (X4) are used as raw materials. The resin wire (X3) passes through the side channel, and the continuous fiber wire (X4) passes through the upper channel. They are then heated, melted, and extruded and placed to achieve 3D printing of composite material components.

6. The fiber-reinforced composite additive manufacturing actuator with real-time external temperature and pressure control according to claim 1, characterized in that: The external auxiliary heating unit and the roller auxiliary extrusion unit are adjusted in real time.

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