Composite material 3D printing terminal suitable for extreme environment

Abstract

The invention belongs to the field of composite material additive manufacturing, and discloses a composite material 3D printing terminal suitable for an extreme environment, which comprises a printing module and a cooling module. Aiming at the problem of plug caused by the fact that a throat pipe in a printing head cannot be discharged in time due to non-convection heat dissipation in a space environment, the throat pipe made of a heterogeneous material is designed, and the speed that heat is transmitted upwards along a nozzle is reduced; in addition, by designing an annular radiator structure capable of allowing a cooling medium to pass through and tightly attached to the outer wall of the throat pipe, the cooling medium continuously and circularly flows in the radiator through a pump so as to take away heat of the throat pipe, and the problem of plug blockage caused by excessive softening of the printing tail end in the space environment is solved. Through cooperative work of the compact printing module and the miniaturized cooling module, the risk of a printing tail end plug is remarkably reduced, and therefore the surface quality and performance of composite material sample piece printing are improved.

Description

Technical Field

[0001] The 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 generating 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 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 by heat conduction and heat radiation. The traditional print head on the ground that uses fan-forced convection to dissipate heat cannot be used in a high vacuum environment. The heat in the throat of the print head cannot be discharged in time, resulting in an increased risk of blockage of the print head, thereby affecting the efficiency and performance of the printed components. Therefore, in order to achieve additive manufacturing in extreme space environments, it is necessary to develop a printing end that can dissipate heat stably to achieve rapid manufacturing of composite materials in space environments.

[0003] In order to develop a printing end suitable for the space environment, patent CN115990995A designed an integrated heating block and heat dissipation block, adding four radiation heat sinks to the original fan forced convection heat dissipation structure, increasing the heat dissipated by the throat to the outside world by increasing the heat dissipation area, and black nickel plating the heat dissipation structure to increase the surface emissivity of the structure to quickly dissipate heat. However, the method of increasing the heat dissipation speed by increasing the heat dissipation area and emissivity has limited improvement in heat dissipation. It has a significant heat dissipation effect within a certain time limit, but as the printing time accumulates, the printing end will cause the wire to soften due to the accumulation of heat, thereby blocking the head; patent CN113001971A uses high heat resistance materials to make passive radiators, so as to slow down the speed of heat transfer upward along the lower end of the nozzle, thereby avoiding the softening of the upper wire caused by heat as much as possible. However, although this method can slow down the heat transfer speed in the external components, it does not take into account that the high heat resistance material will also have a temperature rise after the printing time is prolonged, and it can only play a role within a limited time. Patent CN218084197U designs a high heat resistance throat assembly, which uses industrial pure water with high specific heat capacity as a heat dissipation medium to continuously remove the heat from the throat. However, the pure water in the patent is stationary and the heat dissipation efficiency is not high. Therefore, in order to solve the problem that the radiator in the existing print head cannot continuously dissipate heat or the heat dissipation efficiency is insufficient, it is necessary to develop a print end with heat conduction as the main heat dissipation method to solve the problem of print end blockage caused by low radiation heat dissipation efficiency in a vacuum environment. Summary of the invention

[0004] The present invention is a composite material 3D printing end adapted to extreme environments. It mainly designs a throat made of heterogeneous materials to reduce the speed of heat transfer upward along the nozzle. In addition, by designing a radiator structure with an annular flow channel made of copper, the cooling of the wire material on the upper part of the throat is achieved through the continuous circulation of the internal cooling medium; at the same time, a terminal structure with a pre-treated functional surface is also designed to increase the surface emissivity of the heat dissipation structure, thereby achieving rapid heat dissipation of the entire printing end, solving the problem of plugging caused by excessive softening of the wire material at the printing end in a vacuum environment.

[0005] The technical solution of the present invention:

[0006] A composite material 3D printing terminal adapted to extreme environments, comprising 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 an annular cooling plate and an external circulation pump, and the internal medium is continuously circulated and takes away the heat in the throat through the driving action of the pump, thereby preventing the fiber composite material filament from softening prematurely.

[0007] The printing module A comprises 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 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 outer side of the heating block A6, and is used to heat the heating block A6 and transfer the heat to the nozzle A7, so that the composite material is melted and extruded quickly; 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 threaded fit; the temperature measuring hole A10 is opened on the heating block A6, and is 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, and is 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, and the circulation pump B5 does work 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 high-temperature environment.

[0009] 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 the 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 3MPa.

[0011] The annular cooling fin B1 is manufactured in one piece, 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, so that the emissivity of the component surface is not less than 0.85, so that the heat at the printing end can be radiated outward quickly during the printing process.

[0013] The beneficial effects of the present invention are as follows: through the cooperation 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 quickly increased during heating and quickly decreased during cooling, thereby achieving better energy consumption control. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It 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 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 end adapted to extreme environments of the present invention, which is used for heat dissipation of the throat when the fiber composite material is printed in a vacuum high and low temperature environment;

[0017] In the figure: A1-base, A2-fixed seat, A3-throat, A4-connecting block, A5-heating coil, A6-heating block, A7-nozzle, A8-pressing block, A9-wire port, 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 the 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 monitor the temperature of the nozzle A7 in real time, 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 via 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 via 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 high-temperature environment.

[0024] First, before the experiment begins, the short carbon fiber reinforced PA-based resin filament is inserted into the printing module and then out of the nozzle. The heating rod in the printing module is started, and the temperature to be reached at the nozzle of the printing module is set to 280°C. The 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 temperature at the nozzle exceeds 280°C, the heating rod stops working, and if the temperature is lower than 280°C, the heating rod works to ensure that the temperature at the nozzle fluctuates around 280°C.

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

[0026] The present invention designs a throat made of heterogeneous materials, which reduces the speed of heat transfer upward along the nozzle. In addition, by designing a radiator structure with a flow channel, the cooling of the wire material on the upper part of the throat is achieved through the continuous circulation of the internal cooling medium; at the same time, the structural surface of the printing end is processed to increase the surface emissivity of the heat dissipation structure, thereby achieving rapid heat dissipation of the entire printing end, solving the problem of blockage caused by excessive softening of the wire material at the printing end in a vacuum environment.

Claims

1. A composite material 3D printing end adapted to extreme environments, characterized in that: The composite material 3D printing end comprises a printing module (A) and a cooling module (B); The printing module (A) comprises 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 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) with a gap therebetween; the heating coil (A5) is sleeved on the outer side of the heating block (A6) for heating the heating block (A6) and transferring heat to the nozzle (A7) so as to enable the composite material to be melted and extruded quickly; 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 threaded fit; 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 connected in sequence; 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) is provided with a cooling liquid ... 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 plate (B1) and the circulation pump (B5). The circulation pump (B5) works to make the coolant pass through the cooling plate (B1) and take away the heat accumulated in the throat (A3), so as to achieve rapid cooling of the printing end in a vacuum 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 in one piece, and the coolant inlet (B2) and the coolant outlet (B3) are polished, with the surface roughness not higher than 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 surface of the component, so that the emissivity of the surface of the component is not less than 0.85, so that the heat at the end of the printing process can be quickly radiated outward.

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