A processing method of a pina satellite propulsion system storage tank

Abstract

The application discloses a kind of processing methods of Pina satellite propulsion system storage tank, comprising the following steps: S1, pre-simulation optimization before processing: based on the three-dimensional model of storage tank, heat stress distribution in SLM printing process is simulated by finite element simulation, printing direction and support structure layout are optimized, and additional post-processing removable auxiliary support is added;S2, layering precision printing: using TC4 titanium alloy powder, through SLM equipment, for the cavity wall area and internal mesh support area of storage tank, respectively set different printing process parameters;S3, directional post-processing: first, high-pressure water washing is used to remove residual powder and auxiliary support, then precision grinding is carried out on the double-cavity isolation surface inside the storage tank, and finally, quality detection is carried out on the formed storage tank.The application effectively solves the problems of low forming precision, weak connection strength and poor sealing of small-sized and complex internal cavity storage tank, and the formed storage tank has high precision, reliable sealing, excellent temperature difference cycle performance.

Description

Technical Field

[0001] This invention relates to the fields of additive manufacturing and aerospace device processing technology, and more specifically to a processing method for a storage tank of a Pinna satellite propulsion system. Background Technology

[0002] Pinasatellite propulsion system tanks are small in size (typically <500mL) and complex in structure (including liquid ammonia chambers, vaporization chambers, and internal mesh supports), making it difficult to achieve complex internal cavity molding using traditional processing methods. Existing SLM additive manufacturing technology, when applied to this type of tank, suffers from the following drawbacks: 1. The internal mesh supports are not firmly connected to the cavity wall, making them prone to cracking under orbital temperature differences; 2. Poor uniformity of printed layer thickness leads to insufficient cavity wall sealing; 3. Support removal during post-processing is difficult and easily damages the inner wall of the cavity.

[0003] Chinese invention patent with publication number CN112145683A discloses a new type of pressure vessel device. Although it proposes to use 3D metal printing technology to process the entire pressure vessel, it does not optimize the processing flow for the characteristics of Pinasat tanks such as miniaturization, high precision, and dual-chamber isolation, and therefore cannot meet the stringent processing requirements of Pinasat tanks.

[0004] Therefore, how to provide a processing method for the storage tank of the Pinasatellite propulsion system that can take into account molding accuracy, structural strength and sealing performance is one of the technical problems that urgently need to be solved in this field. Summary of the Invention

[0005] In view of this, the present invention provides a method for processing a storage tank for a Pinna satellite propulsion system, the purpose of which is to solve the problems existing in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for manufacturing a storage tank for a Pinna satellite propulsion system includes the following steps: S1, Pre-processing simulation optimization: Based on the three-dimensional model of the storage tank, the thermal stress distribution during the SLM printing process is simulated by finite element simulation, the printing direction and support structure layout are optimized, and auxiliary supports that can be removed in post-processing are added. S2, Layered Precision Printing: Using TC4 titanium alloy powder and SLM equipment, differentiated printing process parameters are set for the tank cavity wall area and the internal mesh support area respectively. S3, Post-directional processing: First, high-pressure water washing is used to remove residual powder and auxiliary supports. Then, the double-cavity isolation surface inside the storage tank is precision ground. Finally, the formed storage tank is subjected to quality inspection.

[0007] Preferably, in step S2, during the printing process, the dual-cavity isolation surface is made parallel to the printing layer, and post-processing removable auxiliary supports are added to the mesh support structure and the inclined side edge to assist in molding.

[0008] Preferably, in step S2, the interlayer temperature is monitored in real time during the printing process to ensure that the temperature difference is ≤20℃.

[0009] Preferably, in S2, the printing parameters used for the cavity wall printing area are: layer thickness 0.04mm, laser power 350W; and the printing parameters used for the mesh support printing area are: layer thickness 0.06mm, laser power 400W.

[0010] Preferably, in step S3, high-pressure water washing with a pressure of 0.8 MPa is used to clean the residue, and the roughness Ra of the double-cavity isolation surface is ≤0.8 μm after grinding.

[0011] Preferably, X-ray flaw detectors and fluorescent penetrant detectors are used to comprehensively detect internal defects and sealing performance of the molded storage tank.

[0012] The present invention achieves the following technical effects compared to the prior art: 1) This invention optimizes the printing direction and support layout based on finite element simulation, and combines zoned differentiated printing parameters to control the forming accuracy error of the finished storage tank within ±0.04mm, meeting the stringent size requirements of the Pinasatellite propulsion system for small storage tanks. At the same time, by monitoring the interlayer temperature in real time, it avoids dimensional deviations caused by thermal deformation during the printing process, ensuring the consistency of batch processing.

[0013] 2) This invention sets differentiated laser power and layer thickness parameters for the cavity wall and the mesh support area, and with the reasonable layout of auxiliary supports, the connection strength between the internal mesh support and the cavity wall is increased by 40%. After 1000 cycles of on-orbit temperature difference test in an environment of -50℃ to 80℃, the tank showed no cracking or deformation, which solves the technical pain point of weak connection between mesh support and cavity wall in traditional SLM processing and easy cracking under on-orbit temperature difference environment, and is suitable for long-term use in extreme aerospace conditions.

[0014] 3) By employing a directional post-processing technique involving high-pressure water washing and precision grinding, this invention not only improves post-processing efficiency by 30%, but also avoids damage to the inner wall of the cavity. Attached Figure Description

[0015] Figure 1 A 3D view of the storage tanks for the Pinar satellite propulsion system; Figure 2 Side view of the tanks for the Pinar satellite propulsion system; Figure 3 A schematic diagram of the internal mesh support of the liquid ammonia chamber and vaporization chamber; Figure 4 A schematic diagram of adding auxiliary supports to the tanks of the Pinar satellite propulsion system; Figure 5 A schematic diagram of SLM layer printing; Figure 6 This is a flowchart of the directional post-processing process; In the diagram: 1. Liquid ammonia chamber; 2. Vaporization chamber; 3. Solenoid valve installation interface; 4. Separator column; 5. Mesh support; 6. Printed area on the chamber wall; 7. Printed area of ​​the mesh support; 8. Early warning area for thermal stress concentration; 9. Auxiliary support. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] This invention discloses a method for processing a storage tank for a Pinna satellite propulsion system, comprising the following steps: S1, Pre-processing simulation optimization: Based on the three-dimensional model of the storage tank, the thermal stress distribution during the SLM printing process is simulated by finite element simulation, the printing direction and support structure layout are optimized, and auxiliary supports that can be removed in post-processing are added 8. S2, Layered Precision Printing: Using TC4 titanium alloy powder and SLM equipment, differentiated printing process parameters are set for the tank cavity wall area and the internal mesh support area respectively. S3, Post-directional processing: First, high-pressure water washing is used to remove residual powder and auxiliary supports. Then, the double-cavity isolation surface inside the storage tank is precision ground. Finally, the formed storage tank is subjected to quality inspection.

[0018] In S2, during the printing process, the dual-cavity isolation surface is made parallel to the printing layer, and post-processing removable auxiliary supports 8 are added to the mesh support structure and the inclined side edge to assist in molding.

[0019] In S2, the interlayer temperature is monitored in real time during the printing process to ensure that the temperature difference is ≤20℃.

[0020] In S2, the printing parameters used for cavity wall printing area 6 are: layer thickness 0.04mm, laser power 350W; the printing parameters used for mesh support printing area 7 are: layer thickness 0.06mm, laser power 400W.

[0021] In S3, high-pressure water washing at a pressure of 0.8MPa is used to clean the residue, and the roughness Ra of the double-cavity isolation surface is ≤0.8μm after grinding.

[0022] X-ray flaw detector and fluorescence penetrant detector were used to comprehensively inspect the internal defects and sealing performance of the molded storage tank.

[0023] The processing method of the present invention is applicable to the integrated Pinasatellar liquid ammonia-vaporization dual-cavity storage tank, solving the problems of low processing accuracy and poor forming quality of complex internal cavities in miniaturized storage tanks.

[0024] Example 1

[0025] Taking a 1000mL liquid ammonia-vaporization dual-chamber storage tank for a Pinasatellar propulsion system as an example, the tank is made of TC4 titanium alloy and has a rectangular shape with dimensions of 177mm×125mm×87mm. The tank is divided into sections along its width and height: vaporization chamber 2 has a volume of 211mL (serving as a buffer zone for liquid ammonia vaporization), the connecting pipe between the liquid ammonia and vaporization chambers (transition area) has a volume of 1mL, and the remaining area is liquid ammonia chamber 1 (volume of 788mL). The volume of vaporization chamber 2 accounts for 26.8% of the volume of liquid ammonia chamber 1. The two chambers are separated by cylindrical partition columns 4 with a diameter of 4mm and a height of 2mm. The partition columns 4 are arranged in an equilateral triangle array with a hole spacing of 8mm to achieve isolation between the two chambers and stable flow of liquid ammonia. Liquid ammonia chamber 1 has reserved mounting holes for 2 temperature sensors and 1 pressure sensor. The outlet of liquid ammonia chamber 1 has reserved a solenoid valve mounting interface 3 (the interface size is adapted to the installation requirements of the solenoid valve). Vaporization chamber 2 has reserved mounting holes for 1 temperature sensor and 1 pressure sensor.

[0026] The processing method for the aforementioned liquid ammonia-vaporization dual-chamber storage tank of the Pinasatellar propulsion system includes the following steps: Step ①, Pre-simulation optimization before processing: A 3D model of the storage tank was constructed using ANSYS Workbench software, with model parameters consistent with the actual processing: a cuboid shape of 177mm × 125mm × 87mm, an outer shell thickness of 0.5mm, and an internal division into a 211mL vaporization chamber 2 (liquid ammonia vaporization buffer zone), a 1mL liquid ammonia chamber connected to the vaporization chamber via a connecting pipe (transition area), and the remaining liquid ammonia chamber (approximately 788mL). Multiple partition columns 4, each 4mm in diameter and 2mm in height, were arrayed between the two chambers. The liquid ammonia chamber 1 had pre-installed mounting holes for two temperature sensors and one pressure sensor, as well as a solenoid valve mounting interface 3. The vaporization chamber 2 had pre-installed mounting holes for one temperature sensor and one pressure sensor. Based on the model, the SLM printing process was simulated. Considering the overall size of the storage tank, it needed to be tilted at 20°-30° to ensure molding stability. The initial settings were a printing layer thickness of 0.05mm, laser power of 380W, and scanning speed of 1200mm / s. Simulation revealed a thermal stress concentration problem in the partition area between the two chambers. The targeted optimization solutions are as follows: Adjust the printing direction so that the partition surface is parallel to the printing layer to accommodate a 20°-30° tilted placement posture; Add auxiliary supports 8 that can be removed in post-processing to the mesh support 5 inside the liquid ammonia chamber 1 (using a 0.9mm×0.9mm cross-section orthogonal stitching structure with spacing of 4.89mm, 4.9mm, and 5.29mm in the three directions), the tilted edge of the tank, and around the sensor / solenoid valve interface, with the support density controlled at 20%.

[0027] Step ②, precise layer printing: Select a BLT-S310 SLM printer, TC4 powder particle size 15-53μm, powder bed thickness 0.03mm; the printing parameters are set as follows: the printing area 6 (thickness 0.5mm) on the walls of liquid ammonia chamber 1 and vaporization chamber 2 uses a layer thickness of 0.04mm, laser power of 350W, and scanning speed of 1400mm / s; the printing area 7 (0.9mm×0.9mm orthogonal stitching structure, three-way spacing of 4.89mm, 4.9mm, 5.29mm) inside liquid ammonia chamber 1 uses a layer thickness of 0.06mm, laser power of 400W, and scanning speed of 1000mm / s. During the printing process, the interlayer temperature is monitored in real time using an infrared thermometer. When the temperature difference exceeds 20°C, printing is paused until the temperature reaches equilibrium before resuming. The total printing time is 8 hours.

[0028] Step ③, Post-directional treatment: First, rinse the residual powder and auxiliary support 8 inside the cavity with 0.8MPa high-pressure deionized water for 15 minutes. Then, use diamond polishing paste to precisely grind the double-cavity isolation surface at a pressure of 0.3MPa and a speed of 300r / min until the roughness Ra≤0.8μm. Subsequently, perform a strength pressure test at a pressure of 3.6MPa, holding the pressure for 30 minutes without deformation or leakage. Finally, use a helium mass spectrometer leak detector to perform a helium leak detection test to ensure a leak detection rate of less than 10%. -6 Pa·m³ / s, and finally, internal defects were detected by X-ray detector (the qualified standard is defect size ≤0.1mm), and the sealing performance was verified by fluorescence detector.

[0029] Implementation and verification: The finished storage tanks had a forming accuracy error of ±0.04mm, and performance verification met the design requirements: no leakage after holding pressure at 1MPa for 30 minutes, no deformation or leakage after holding pressure at 3.6MPa for 30 minutes during a strength pressure test, and a helium leak detection rate of 8×10⁻⁶. -7 Pa·m³ / s (better than 10) -6 (The index requirement is Pa·m³ / s); after 1000 cycles in a temperature difference environment of -50℃ to 80℃, the mesh support is well connected to the cavity wall without cracking; the post-processing efficiency is 32% higher than that of the traditional process, and there is no damage to the inner wall of the cavity.

[0030] This invention provides a method for processing tanks for PINAS satellite propulsion systems that balances molding accuracy, structural strength, and sealing performance. It is adapted to the complex structure of dual-cavity integration and internal mesh support. The resulting tank has a molding accuracy error of ≤±0.05mm, cavity wall sealing performance that meets the requirement of no leakage under 1MPa pressure, 40% improved connection strength between internal mesh support and cavity wall, no cracking after 1000 cycles in an on-orbit temperature difference environment (-50℃~80℃), 30% improved post-processing efficiency, and avoids damage to the inner wall of the cavity.

[0031] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for processing a storage tank for a Pinasatellite propulsion system, characterized in that, Includes the following steps: S1, Pre-processing simulation optimization: Based on the three-dimensional model of the storage tank, the thermal stress distribution during the SLM printing process is simulated by finite element simulation, the printing direction and support structure layout are optimized, and auxiliary supports that can be removed in post-processing are added. S2, Layered Precision Printing: Using TC4 titanium alloy powder and SLM equipment, differentiated printing process parameters are set for the tank cavity wall area and the internal mesh support area respectively. S3, Post-directional processing: First, high-pressure water washing is used to remove residual powder and auxiliary supports. Then, the double-cavity isolation surface inside the storage tank is precision ground. Finally, the formed storage tank is subjected to quality inspection.

2. The processing method of a storage tank for a picosatellite propulsion system according to claim 1, characterized in that, In S2, during the printing process, the dual-cavity isolation surface is made parallel to the printing layer, and post-processing removable auxiliary supports are added to the mesh support structure and the inclined side edge to assist in molding.

3. The processing method of a storage tank for a picosatellite propulsion system according to claim 1, characterized in that, In step S2, the interlayer temperature is monitored in real time during the printing process to ensure that the temperature difference is ≤20℃.

4. The processing method of a storage tank for a picosatellite propulsion system according to claim 1, characterized in that, In S2, the printing parameters used for the cavity wall printing area are: layer thickness 0.04mm, laser power 350W; the printing parameters used for the mesh support printing area are: layer thickness 0.06mm, laser power 400W.

5. The processing method of a storage tank for a Pinnacle satellite propulsion system according to claim 1, characterized in that, In step S3, high-pressure water washing at a pressure of 0.8 MPa is used to clean the residue, and the roughness Ra of the double-cavity isolation surface is ≤0.8 μm after grinding.

6. The processing method of a storage tank for a picosatellite propulsion system according to claim 1, characterized in that, In step S3, an X-ray flaw detector and a fluorescent penetrant flaw detector are used to comprehensively inspect the internal defects and sealing performance of the molded storage tank.

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