A composite material 3D printing terminal adapted to extreme environments

Abstract

The present invention belongs to the field of composite material additive manufacturing, and discloses a composite material 3D printing end adapted to extreme environments, including a printing module and a cooling module. In order to solve the problem of clogging caused by the inability of the throat in the print head to be discharged in time due to the lack of convection heat dissipation in the space environment, a throat composed of heterogeneous materials is designed to slow down the speed of heat transfer upward along the nozzle; in addition, by designing an annular radiator structure that can pass cooling medium and is tightly attached to the outer wall of the throat, the cooling medium is continuously circulated in the radiator through a pump to take away the heat of the throat, thereby solving the clogging problem caused by excessive softening of the printing end in the space environment. The present invention significantly reduces the risk of clogging of the printing end by cooperating with a compact printing module and a miniaturized cooling module, thereby improving the surface quality and performance of printed composite samples.

Description

Technical Field

[0001] The present invention belongs to the field of composite material additive manufacturing and relates to a composite material 3D printing terminal adapted to extreme environments. Background Art

[0002] On-orbit additive manufacturing refers to the technology of directly printing and producing parts using portable materials or extraterrestrial resources in space. This technology has the advantages of reducing launch costs and improving mission flexibility, and is an effective way to achieve the on-orbit construction of large space structures / facilities. However, unlike ground-based additive manufacturing technology, extravehicular on-orbit manufacturing technology needs to face the harsh environment of high vacuum and high and low temperatures in space. In a high vacuum environment, objects can only dissipate heat through heat conduction and thermal radiation. Traditional print heads on the ground that use fan-forced convection to dissipate heat cannot be used in high vacuum environments. The heat in the throat of the print head cannot be discharged in time, resulting in an increased risk of print head clogging, which affects the efficiency and performance of the printed components. Therefore, in order to achieve additive manufacturing in the extreme environment of space, it is necessary to develop a printing terminal that can dissipate heat stably to achieve rapid manufacturing of composite materials in space environments.

[0003] To develop a printhead suitable for space environments, patent CN115990995A designed an integrated heating block and heat sink. Four radiating fins were added to the existing fan-forced convection heat dissipation structure. This increased the heat dissipation area by increasing the heat loss from the nozzle to the outside world. The heat dissipation structure was then black-nickel-plated to increase its surface emissivity, rapidly dissipating heat. However, increasing the heat dissipation rate by increasing the heat dissipation area and emissivity has limited benefits. While it can achieve significant heat dissipation within a certain timeframe, as printing time accumulates, the printhead can soften due to accumulated heat, leading to blockage. Patent CN113001971A uses a passive heat sink made of a high-resistance material to slow the transfer of heat upward from the lower end of the nozzle, minimizing heat-induced softening of the upper filament. While this approach can slow heat transfer in the external components, it fails to account for the temperature rise of the high-resistance material over extended printing times, effectively limiting its effectiveness for a limited time. Patent CN218084197U designs a high-thermal-resistance throat assembly that continuously removes heat from the throat using industrial pure water, a heat dissipation medium with a high specific heat capacity. However, the pure water in this patent is stationary, resulting in low heat dissipation efficiency. Therefore, to address the issue of the existing printhead radiator's inability to dissipate heat continuously or inefficiently, a printhead tip with heat conduction as the primary heat dissipation method is needed to address the issue of printhead tip blockage caused by the low efficiency of radiant heat dissipation in vacuum environments. Summary of the Invention

[0004] This invention proposes a composite 3D printing tip suitable for extreme environments. The main feature is a throat constructed of heterogeneous materials, which reduces the rate of heat transfer upward along the nozzle. Furthermore, a heat sink structure with an annular flow channel machined from copper is designed to cool the filament above the throat through the continuous circulation of an internal cooling medium. The tip also features a pre-treated surface to increase the surface emissivity of the heat dissipation structure, thereby achieving rapid heat dissipation throughout the entire printing tip. This solves the problem of clogging caused by excessive softening of the filament in vacuum environments.

[0005] The technical solution of the present invention:

[0006] A composite material 3D printing terminal adapted to extreme environments includes a printing module A and a cooling module B. The printing module A is mainly composed of an annular heating ring and a heating block with high thermal conductivity, which effectively improves the melting efficiency of the fiber composite material and the uniformity of heat transfer. The cooling module B is mainly composed of annular cooling fins and an external circulation pump. The pump drives the internal medium to continuously circulate and remove heat from the throat, preventing the fiber composite material filament from softening prematurely.

[0007] The printing module A includes a base A1, a fixing base A2, a throat A3, a connecting block A4, a heating coil A5, a heating block A6, a nozzle A7, a pressing block A8, a wire inlet A9 and a thermocouple temperature measuring hole A10; the throat A3 is located inside the printing module A and is fixed on the lower surface of the base A1; the fixing base A2 is connected to the base A1 by a thread; the connecting block A4 is connected to the fixing base A2, and a gap is left between the two; the heating coil A5 is sleeved on the outside of the heating block A6, used to heat the heating block A6 and transfer heat to the nozzle A7, so that the composite material is quickly melted and extruded; the heating block A6 is connected to the connecting block A4 by a thread, and the nozzle A7 is connected to the heating block A6 by a thread; the temperature measuring hole A10 is opened on the heating block A6, used to place a thermocouple to monitor the temperature of the nozzle A7 in real time; the wire inlet A9 is located on the upper surface, used to insert the composite material wire; the wire inlet A9, the throat A3 and the nozzle A7 are connected in sequence;

[0008] The cooling module B includes a cooling fin B1, a coolant inlet B2, a coolant outlet B3, a coolant circulation pipe B4, a circulation pump B5, an adapter B6, a circulation pump inlet B7 and a circulation pump outlet B8; the cooling fin B1 is provided with a coolant inlet B2 and a coolant outlet B3, and the circulation pump B5 is provided with a circulation pump inlet B7 and a circulation pump outlet B8; the coolant inlet B2 is connected to the coolant circulation pipe B4, the coolant circulation pipe B4 is connected to the circulation pump outlet B8 through the adapter B6, the coolant outlet B3 is connected to the coolant circulation pipe B4, the coolant circulation pipe B4 is connected to the circulation pump inlet B7 through the adapter B6, and a complete circulation loop of the coolant is formed through the cooling fin B1 and the circulation pump B5. The circulation pump B5 works to make the coolant pass through the cooling fin B1 and take away the heat accumulated in the throat A3, thereby realizing rapid cooling of the printing end in a vacuum and high-temperature environment.

[0009] The cooling module B uses an external circulation pump to drive the coolant to dissipate heat. To ensure that the heat dissipation process meets actual needs, the actual cooling load Q, coolant specific heat capacity C, coolant density ρ, temperature change ΔT, coolant flow rate v in the tube, and coolant circulation tube diameter d must meet the following conditions:

[0010] The coolant circulation pipe B4 is made of a steel wire reinforced nylon pipe with a pressure resistance greater than 3 MPa.

[0011] The annular cooling fin B1 is manufactured as a whole, and the coolant inlet B2 and the coolant outlet B3 are polished, and the surface roughness is not higher than Ra1.6.

[0012] The outer surface of the printing module A is oxidized and blackened to increase the emissivity of the component surface, achieving a surface emissivity of not less than 0.85, so that the heat at the printing end can be quickly radiated outward during the printing process.

[0013] The beneficial effects of the present invention are as follows: through the coordinated operation of the annular heating ring, the annular cooling plate and the external circulation pump, the heat dissipation efficiency of the fiber composite material printing end is significantly improved, and the problem of clogging caused by softening of the wire is solved; and by adjusting the flow rate of the cooling medium, the heat can be rapidly increased during heating and rapidly decreased during cooling, thereby achieving better energy consumption control. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the overall structure of a composite material 3D printing terminal adapted to extreme environments of the present invention, which is suitable for additive manufacturing of fiber composite materials in vacuum and high and low temperature environments;

[0015] Figure 2 This is a schematic diagram of the structure of a printing module of a composite material 3D printing terminal adapted to extreme environments of the present invention, which is used for melt printing of fiber composite materials;

[0016] Figure 3 This is a schematic diagram of the cooling module structure of a composite material 3D printing terminal adapted to extreme environments according to the present invention, which is used to dissipate heat from the throat when printing fiber composite materials in vacuum high and low temperature environments;

[0017] In the figure: A1-base, A2-fixing seat, A3-throat, A4-connecting block, A5-heating coil, A6-heating block, A7-nozzle, A8-pressing block, A9-wire outlet, A10-thermocouple temperature measuring hole; B1-cooling fin, B2-coolant inlet, B3-coolant outlet, B4-coolant circulation pipe, B5-circulating pump, B6-adapter, B7-circulating pump inlet, B8-circulating pump outlet. DETAILED DESCRIPTION

[0018] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0019] Example 1

[0020] Taking the printing of PA-CF composite material samples in a high-temperature vacuum tank as an example, short carbon fiber reinforced PA resin-based composite materials were selected for printing. According to the material properties, appropriate process parameters were selected to carry out this example: the nozzle temperature was 280°C and the coolant flow rate was 0.3m / s.

[0021] A composite material 3D printing terminal adapted to extreme environments, comprising a printing module and a cooling module;

[0022] The printing module includes a base A1, a fixing seat A2, a throat A3, a connecting block A4, a heating coil A5, a heating block A6, a nozzle A7, a pressing block A8, a wire inlet A9, and a thermocouple temperature measuring hole A10; the throat A3 is fixed to the base A1 by a top screw, the fixing seat A2 is connected to the base A1 by a thread, the connecting block A4 is connected to the fixing seat A2 by a screw, the heating coil A5 is sleeved on the outside of the heating block A6, and is used to heat the heating block A6 and transfer heat to the nozzle A7, so that the fiber composite material is quickly melted and extruded, the heating block A6 is connected to the connecting block A4 by a thread, the nozzle A7 is connected to the heating block A6 by a thread, the temperature measuring hole A10 is used to place a thermocouple to perform real-time temperature monitoring of the nozzle A7, and the wire inlet A9 is used to insert the fiber composite material wire;

[0023] The cooling module includes a cooling fin B1, a coolant inlet B2, a coolant outlet B3, a coolant circulation pipe B4, a circulation pump B5, an adapter B6, a circulation pump inlet B7, and a circulation pump outlet B8; the coolant inlet B2 is connected to the coolant circulation pipe B4, the coolant circulation pipe B4 is connected to the circulation pump outlet B8 through the adapter B6, the coolant outlet B3 is connected to the coolant circulation pipe B4, the coolant circulation pipe B4 is connected to the circulation pump inlet B7 through the adapter B6, and a complete circulation loop of the coolant is formed through the cooling fin B1 and the circulation pump B5. The circulation pump works to make the coolant pass through the cooling fin B1 and take away the heat accumulated in the throat A3, thereby realizing rapid cooling of the printing end in a vacuum and high-temperature environment.

[0024] Before the experiment begins, short carbon fiber-reinforced PA-based resin filament is threaded into the print module and then out of the nozzle. The heater in the print module is activated, and the temperature at the print module nozzle is set to 280°C. A K-type thermocouple measures the temperature in real time and feeds the temperature back to the temperature controller. After five minutes of heating, the entire nozzle reaches 280°C. During the entire heating process, if the nozzle temperature exceeds 280°C, the heater stops working. If the temperature is below 280°C, the heater starts working, thus ensuring that the nozzle temperature fluctuates around 280°C.

[0025] At the same time, the external circulation pump is turned on to circulate the coolant in the cooling module, removing the heat from the throat pipe at the upper end of the printing module, so that the temperature at the throat pipe is maintained at around 50°C, which is lower than the melting temperature of the short carbon fiber reinforced PA resin filament. This ensures that the fiber composite material filament can pass through normally and melts quickly at the nozzle. The molten filament is controlled by the printing equipment to melt and stack along a specific trajectory, and finally a fiber composite material printed sample with good performance is obtained in a high-temperature vacuum tank.

[0026] This invention designs a throat made of heterogeneous materials, reducing the rate of heat transfer upward along the nozzle. Furthermore, a heat sink structure with a flow channel continuously circulates a cooling medium within it, cooling the filament above the throat. The surface of the printhead is also treated to increase the surface emissivity of the heat dissipation structure, thereby achieving rapid heat dissipation throughout the entire printhead. This solves the problem of clogging caused by excessive softening of the filament in a vacuum environment.

Claims

1. A composite material 3D printing terminal adapted to extreme environments, characterized in that: The composite material 3D printing terminal includes a printing module (A) and a cooling module (B); The printing module (A) comprises a base (A1), a fixing seat (A2), a throat (A3), a connecting block (A4), a heating coil (A5), a heating block (A6), a nozzle (A7), a pressing block (A8), a wire inlet (A9) and a thermocouple temperature measuring hole (A10); the throat (A3) is located inside the printing module (A) and fixed on the lower surface of the base (A1); the fixing seat (A2) is connected to the base (A1) via a thread; the connecting block (A4) is connected to the fixing seat (A2) with a gap therebetween; the heating coil (A5) is sleeved on the outside of the heating block (A6) to heat the heating block (A6) and transfer heat to the nozzle (A7) to enable the composite material to be quickly melted and extruded; the heating block (A6) is connected to the connecting block (A4) via a thread, and the nozzle (A7) is connected to the heating block (A6) via a thread; A temperature measuring hole (A10) is opened on the heating block (A6) for placing a thermocouple to monitor the temperature of the nozzle (A7) in real time; a wire inlet (A9) is located on the upper surface for inserting composite wire; the wire inlet (A9), the throat (A3) and the nozzle (A7) are sequentially connected; The cooling module (B) comprises a cooling fin (B1), a cooling liquid inlet (B2), a cooling liquid outlet (B3), a cooling liquid circulation pipe (B4), a circulation pump (B5), an adapter (B6), a circulation pump inlet (B7) and a circulation pump outlet (B8); the cooling fin (B1) is provided with a cooling liquid inlet (B2) and a cooling liquid outlet (B3); the circulation pump (B5) is provided with a circulation pump inlet (B7) and a circulation pump outlet (B8); the cooling liquid inlet (B2) is connected to the cooling liquid circulation pipe (B4); the cooling liquid circulation pipe (B5 ... The ring tube (B4) is connected to the circulation pump outlet (B8) through the adapter (B6), the coolant outlet (B3) is connected to the coolant circulation pipe (B4), the coolant circulation pipe (B4) is connected to the circulation pump inlet (B7) through the adapter (B6), and a complete circulation loop of the coolant is formed through the cooling fin (B1) and the circulation pump (B5). The circulation pump (B5) works to make the coolant pass through the cooling fin (B1) and take away the heat accumulated in the throat (A3), thereby realizing rapid cooling of the printing end in a vacuum and high-temperature environment.

2. The composite material 3D printing tip according to claim 1, characterized in that: The cooling module (B) is driven by an external circulation pump to dissipate heat through the coolant. To ensure that the heat dissipation process meets actual needs, the actual cooling load Q, coolant specific heat capacity C, coolant density ρ, temperature change ΔT, coolant flow rate v in the tube, and coolant circulation tube diameter d must meet the following conditions:

3. The composite material 3D printing tip according to claim 1, characterized in that: The coolant circulation pipe (B4) is made of a steel wire reinforced nylon pipe with a pressure resistance greater than 3MPa.

4. The composite material 3D printing tip according to claim 1, characterized in that: The annular cooling fin (B1) is manufactured as a whole, and the coolant inlet (B2) and the coolant outlet (B3) are polished, with the surface roughness not exceeding Ra1.

6.

5. The composite material 3D printing tip according to claim 1, characterized in that: The outer surface of the printing module (A) is oxidized and blackened to increase the emissivity of the component surface, achieving a surface emissivity of not less than 0.85, so that the heat at the printing end can be quickly radiated outward during the printing process.

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