Gas-liquid pulse cleaning method and equipment for additive manufacturing parts

Abstract

The invention discloses a gas-liquid pulse cleaning method and gas-liquid pulse cleaning equipment for additive manufacturing parts, and relates to the technical field of channel cleaning, and the gas-liquid pulse cleaning method comprises the following steps that a part blank to be cleaned is fixed, a runner is kept through, a low-foam neutral metal cleaning agent is introduced into the runner, and treatment is conducted in the mode that standing permeation and circulating flow are alternately conducted; then low-pressure clean compressed air is adopted for purging from one end of the flow channel, and loose and non-molten particles in the flow channel are removed; the pretreated part is placed in a gas-liquid pulse cleaning cavity, and a gas-liquid pulse spray head is aligned with at least one inlet / outlet of a flow channel and does not stretch into the flow channel; a gas-liquid pulse generation system is started, and pulse parameters are adjusted in a segmented mode according to the hole diameter and structural characteristics of the flow channel; firstly, compressed air is used for blowing the runner in a segmented mode according to the thickness of the runner, and then the part is put into a hot air circulating oven to be dried; and carrying out cleaning detection on the runner section, and when the particle residual quantity of the runner section is smaller than a preset threshold value, judging that the cleaning is qualified.

Description

Technical Field

[0001] This invention relates to the field of channel cleaning technology, and in particular to a gas-liquid pulse cleaning method and equipment for additive manufacturing parts. Background Technology

[0002] Metal powder additive manufacturing technology can form slender microchannel parts (such as fuel nozzles for aero-engines and servo valve cores), or lattice structure parts with high weight reduction but low strength. However, residual particles in the internal cavity of the formed part, such as semi-molten particles adhering to the wall surface at high temperatures, and unmolten particles stuck in the middle / end of the flow channel, are difficult to remove and can affect the service performance of the part, cause system contamination, and other problems. Existing cleaning processes have certain limitations. The cleaning medium cannot penetrate the entire flow path. Due to the small diameter and long length of the microchannels, the pressure of the cleaning medium in traditional high-pressure water jets decreases by 50%–70% within the channel, resulting in insufficient cleaning force at the end and a high particle residue rate. Furthermore, it is difficult for the nozzle to perfectly match the channel, preventing it from reaching the channel and creating a large cleaning blind zone. Additive manufacturing parts have a high risk of substrate damage, and the microchannel walls are thin, typically 0.5–2 mm. Traditional high-pressure cleaning uses pressures >20 MPa, which easily leads to channel deformation and wall cracking, requiring extremely high control over the damage rate in the cleaning process. However, low-pressure cleaning cannot remove semi-molten particles. Metal particles easily clog the channels. High-pressure purging during the pretreatment stage can cause loose particles to form "bridging blockages" in the middle of the microchannel, preventing subsequent cleaning medium from passing through and exacerbating residue. Room-temperature cleaning agents cannot soften the adhesive layer of semi-molten particles, making subsequent cleaning difficult. Summary of the Invention

[0003] The main objective of this invention is to propose a gas-liquid pulse cleaning method and equipment for additive manufacturing parts, aiming to solve the technical problem of precise cleaning of complex structures and complex flow channels.

[0004] To achieve the above objectives, the present invention provides a gas-liquid pulse cleaning method and apparatus for additively manufactured parts, comprising the following steps: S1. Low-pressure immersion pretreatment: Fix the blank of the part to be cleaned and keep the microchannel open. Introduce a low-foaming neutral metal cleaning agent into the channel and treat it by alternating static penetration and circulation. Then, use low-pressure clean compressed air to blow from one end of the channel to remove loose unmelted particles in the channel. At the same time, use ultrasonic assistance to shake out some unmelted particles and weaken the bonding force of semi-melted particles.

[0005] S2, Gas-liquid pulse main cleaning: Place the pre-treated parts into the gas-liquid pulse cleaning chamber, and align the gas-liquid pulse nozzle with at least one inlet / outlet of the flow channel without extending into the flow channel; start the gas-liquid pulse generation system and adjust the pulse parameters in segments according to the orifice diameter and structural characteristics of the flow channel. S3. Targeted post-treatment: First, use compressed air to blow through the flow channel according to the coarseness and fineness of the flow channel, and then put the parts into a hot air circulating oven for drying; test the flow channel section, and when the amount of residual particles in any flow channel section is less than the preset threshold calculated according to the inner wall area of ​​the flow channel, it is judged as qualified cleaning.

[0006] In one embodiment, in step S1: The low-foaming neutral metal cleaning agent has a temperature of 60-80℃, a concentration of 3%-5%, and a pH of 7.5-8.5. The static infiltration time and the circulation time are both 1~3 min, and the total soaking time is 6~30 min; The pressure of the low-pressure clean compressed air is 0.4~0.8 MPa.

[0007] In one embodiment, in step S2: The distance between the gas-liquid pulse nozzle and the flow channel port is 5~15 mm, and the nozzle does not need to extend into the flow channel. The flow channel features include aperture variations and staggered structures.

[0008] In one embodiment, in step S3: During the segmented compressed air purging, the purging pressure for the fine segment is 0.3~0.4 MPa, and the purging pressure for the coarse segment is 0.4~0.5 MPa, with each segment purging lasting 2~3 minutes. The temperature of the hot air circulating oven is 80~100 ℃, the wind speed is 1~2 m / s, and the drying time is 30~50 minutes. The cleanliness is evaluated using a rinsing method and a particle counting method. The preset thresholds are as follows: particles with a particle size of 5≤X<50 μm are disregarded; particles with a particle size of 50≤X<100 μm do not exceed 130; particles with a particle size of 100≤X<150 μm do not exceed 64; particles with a particle size of 150≤X<200 μm do not exceed 32; particles with a particle size of 200≤X<400 μm do not exceed 16; particles with a particle size of 400≤X<600 μm do not exceed 1; and particles with a particle size of X≥600 μm are excluded.

[0009] In one embodiment, in step S1: The low-foaming neutral metal cleaning agent is composed of 3%~5% isomeric tridecyl alcohol polyoxyethylene ether, 1%~2% aminotrimethylene phosphonic acid, 0.1%~0.3% organosilicon defoamer, and the balance deionized water.

[0010] In one embodiment, in step S1: The pressure fluctuation of the low-pressure clean compressed air is ≤ ±0.05 MPa; a flow sensor is used to monitor the flow rate at the outlet of the flow channel. When the flow rate drops sharply by ≥30%, the purging is stopped and 0.1 MPa air is introduced in reverse to clear the blockage.

[0011] In one embodiment, in step S1: It also includes ultrasonic treatment, with an ultrasonic frequency of 25~35 kHz; the ultrasonic frequency range can weaken the connection of 10~100 μm metal particles in a semi-molten state.

[0012] In one embodiment, in step S2: The segmented adjustment pulse parameters are as follows: for thin or constricted sections with an aperture ≤ 6 mm, a pulse pressure of 3.5~4 MPa, a frequency of 15~25 Hz, a gas-liquid volume ratio of 25~35:1, and a cleaning time of 4~6 min are used; for coarse or bifurcated sections with an aperture > 6 mm, a pulse pressure of 1.5~2 MPa, a frequency of 5~15 Hz, a gas-liquid volume ratio of 10~20:1, and a cleaning time of 6~10 min are used. During the cleaning process, the gas-liquid ratio is switched every 3 to 5 minutes, and the gas-liquid ratio switching is controlled within 20% ratio difference; at the same time, 0.1% to 0.3% of biodegradable microbubble generator is added to the cleaning solution.

[0013] In one embodiment, in step S2: The gas-liquid pulse generation system can achieve independent or linkage adjustment of pulse pressure 1.5~4 MPa, frequency 5~25 Hz, and gas-liquid ratio 10~35:1, with an adjustment response time ≤10 ms; the liquid in the gas-liquid pulse is a low-foaming neutral metal cleaning agent that has undergone 5 μm precision filtration.

[0014] In a second aspect, the present invention provides a gas-liquid pulse cleaning device for additively manufactured parts, including a part fixing mechanism, a pretreatment module, a gas-liquid pulse main cleaning module, and a post-treatment module. A part fixing mechanism is used to fix the powder additive part blank to be cleaned; The pretreatment module includes a cleaning agent supply component and a low-pressure purging component. The cleaning agent supply component is used to introduce a low-foaming neutral metal cleaning agent into the flow channel and can achieve alternating operation of static penetration and circulating flow. The low-pressure purging component is used to introduce clean compressed air into the flow channel to remove loose unmelted particles in the flow channel. The gas-liquid pulse main cleaning module includes a gas-liquid pulse cleaning chamber, a gas-liquid pulse nozzle, and a gas-liquid pulse generating system. The gas-liquid pulse cleaning chamber is used to accommodate pre-treated parts. The gas-liquid pulse nozzle is disposed in the cleaning chamber and can be aligned with at least one inlet or outlet of the flow channel. The gas-liquid pulse generating system is connected to the gas-liquid pulse nozzle and can adjust the pulse parameters in segments according to the flow channel characteristics. The post-processing module includes a segmented purging assembly, a hot air drying assembly, and a detection assembly. The segmented purging assembly is used to introduce compressed air into the flow channel in segments. The hot air drying assembly is used to dry the purged parts. The detection assembly is used to perform targeted detection on each flow channel segment to determine whether the particle residue in the flow channel meets the qualified standard.

[0015] The gas-liquid pulse cleaning method provided by this invention effectively solves the technical problems existing in the prior art, such as insufficient penetration of the cleaning medium, easy damage to parts, easy clogging of the flow channel, and difficulty in removing semi-molten particles. This method uses low-pressure pulse pretreatment to effectively soften semi-molten particles through alternating penetration and circulation of the cleaning agent, and low-pressure purging to avoid particle bridging and clogging, laying the foundation for deep cleaning. In the main gas-liquid pulse cleaning stage, segmentally adjustable pulse pressure is applied from outside the flow channel, allowing the cleaning medium to effectively act on the entire narrow flow channel, ensuring sufficient cleaning force while significantly reducing the risk of damage to the thin-walled structure of additively manufactured parts. Subsequent targeted segmented purging and drying further ensure the cleanliness and dryness of the flow channel. The entire method, through the synergy between steps, achieves efficient and safe cleaning of complex internal flow channels, effectively removing residual particles and ensuring the service reliability of precision parts and the cleanliness of the system. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 A schematic flowchart of a gas-liquid pulse cleaning method for additively manufactured parts provided by the present invention; Figure 2 A two-dimensional schematic diagram of the complex flow channel cavity of a proportional valve manufactured using powder additive manufacturing. Figure 3 This is a schematic diagram showing the contrast between the gold content on the inner cavity surface before and after cleaning in Example 2; Figure 4 This is a schematic diagram of the cleaning and testing of the maximum reflective particles and filter screen in Example 2; Figure 5 This is a schematic diagram of the maximum reflective particles and filter screen during the cleaning test, serving as a comparative example.

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that if directional indicators (such as up, down, left, right, front, back, etc.) are involved in the embodiments of this invention, these directional indicators are only used to explain the relative positional relationships and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly. Unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0021] Furthermore, if the embodiments of the present invention involve descriptions using terms such as "first," "second," etc., these descriptions are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Furthermore, the use of "and / or" or "and / or" throughout the text includes three parallel options; for example, "A and / or B" includes option A, option B, or options where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0022] The present invention proposes a gas-liquid pulse cleaning method and apparatus for additively manufactured parts, comprising the following steps: S1. Low-pressure immersion pretreatment: Fix the blank of the part to be cleaned and keep the microchannel open. Introduce low-foaming neutral metal cleaning agent into the channel and treat it by alternating static penetration and circulation. Then, use low-pressure clean compressed air to blow from one end of the channel to remove loose unmelted particles in the channel. S2, Gas-liquid pulse main cleaning: Place the pre-treated parts into the gas-liquid pulse cleaning chamber, and align the gas-liquid pulse nozzle with at least one inlet / outlet of the flow channel without extending into the flow channel; start the gas-liquid pulse generation system and adjust the pulse parameters in segments according to the orifice diameter and structural characteristics of the flow channel. S3. Targeted post-treatment: First, use compressed air to blow through the flow channel according to the coarseness and fineness of the flow channel, and then put the parts into the hot air circulating oven for drying; perform targeted detection on each flow channel segment, and when the particle residue in any flow channel segment is less than the preset threshold calculated according to the inner wall area of ​​the flow channel, it is judged as qualified cleaning.

[0023] In one embodiment, in step S1: The temperature range for low-foaming neutral metal cleaning agents is 60-80 ℃, the concentration is 3%-5%, and the pH is 7.5-8.5. The time for static infiltration and the time for circulation are both 1~3 min, and the total soaking time is 6~30 min; The pressure of low-pressure clean compressed air is 0.4~0.8 MPa.

[0024] In one embodiment, in step S2: The distance between the gas-liquid pulse nozzle and the flow channel port is 5~15 mm, and the nozzle does not need to extend into the flow channel; Flow channel characteristics include aperture variation and staggered structure.

[0025] In one embodiment, in step S3: When purging with compressed air in stages, the purging pressure for the fine stage is 0.3~0.4 MPa, and the purging pressure for the coarse stage is 0.4~0.5 MPa, with each stage purging time being 2~3 min. The temperature of the hot air circulating oven is 80~100 ℃, the air velocity is 1~2 m / s, and the drying time is 30~50 min. The cleanliness is evaluated using the rinsing method and the particle counting method. The preset thresholds are: particles with 5≤X<50 μm are not counted, particles with 50≤X<100 μm do not exceed 130, particles with 100≤X<150 μm do not exceed 64, particles with 150≤X<200 μm do not exceed 32, particles with 200≤X<400 μm do not exceed 16, particles with 400≤X<600 μm do not exceed 1, and particles with X≥600 μm are excluded.

[0026] In one embodiment, in step S1: The low-foaming neutral metal cleaning agent consists of 3%~5% isomeric tridecyl alcohol polyoxyethylene ether, 1%~2% aminotrimethylene phosphonic acid, 0.1%~0.3% organosilicon defoamer, and the balance deionized water.

[0027] In one embodiment, in step S1: The pressure fluctuation of low-pressure clean compressed air is ≤ ±0.05 MPa; a flow sensor is used to monitor the flow rate at the outlet of the flow channel. When the flow rate drops sharply by ≥30%, the purging is stopped and 0.1 MPa air is introduced in reverse to clear the blockage.

[0028] In one embodiment, in step S1: It also includes ultrasonic treatment. The ultrasonic pretreatment equipment is model JP-300ST, and the ultrasonic frequency is 25~35 kHz. Within the ultrasonic frequency range, it can weaken the connection of 10~100 μm metal particles in a semi-molten state.

[0029] In one embodiment, in step S2: The specific pulse parameters for segmented adjustment are as follows: For thin or constricted sections with an aperture ≤ 6 mm, use a pulse pressure of 3.5~4 MPa, a frequency of 15~25 Hz, a gas-liquid volume ratio of 25~35:1, and a cleaning time of 4~6 min; for coarse or bifurcated sections with an aperture > 6 mm, use a pulse pressure of 1.5~2 MPa, a frequency of 5~15 Hz, a gas-liquid volume ratio of 10~20:1, and a cleaning time of 6~10 min. During the cleaning process, the gas-liquid ratio is switched every 3 to 5 minutes, and the gas-liquid ratio switching is controlled within 20% ratio difference; at the same time, 0.1% to 0.3% of biodegradable microbubble generator is added to the cleaning solution.

[0030] In one embodiment, in step S2: The gas-liquid pulse generation system can achieve independent or linkage adjustment of pulse pressure 1.5~4 MPa, frequency 5~25 Hz, and gas-liquid ratio 10~35:1, with an adjustment response time ≤10 ms; the liquid in the gas-liquid pulse is a low-foaming neutral metal cleaning agent that has undergone 5 μm precision filtration.

[0031] In a second aspect, the present invention provides a gas-liquid pulse cleaning device for additively manufactured parts, including a part fixing mechanism, a pretreatment module, a gas-liquid pulse main cleaning module, and a post-treatment module. A part fixing mechanism is used to fix the powder additive part blank to be cleaned; The pretreatment module includes a cleaning agent supply component and a low-pressure purging component. The cleaning agent supply component is used to introduce low-foaming neutral metal cleaning agent into the flow channel and can realize alternating operation of static penetration and circulating flow. The low-pressure purging component is used to introduce clean compressed air into the flow channel to remove loose unmelted particles in the flow channel. The main gas-liquid pulse cleaning module includes a gas-liquid pulse cleaning chamber, a gas-liquid pulse nozzle, and a gas-liquid pulse generation system. The gas-liquid pulse cleaning chamber is used to accommodate pre-treated parts. The gas-liquid pulse nozzle is located inside the cleaning chamber and can be aligned with at least one inlet or outlet of the flow channel. The gas-liquid pulse generation system is connected to the gas-liquid pulse nozzle and can adjust the pulse parameters in segments according to the flow channel characteristics. The gas-liquid pulse cleaning equipment model is the Sanpu KMX-90 pulse cleaner with an additional gas-liquid mixing module.

[0032] The post-processing module includes a segmented purging assembly, a hot air drying assembly, and a detection assembly. The segmented purging assembly introduces compressed air into the flow channel in segments. The hot air drying assembly dries the purged parts. The detection assembly performs targeted detection on each flow channel segment to determine whether the residual particles in the flow channel meet the acceptable standards. The purging assembly and hot air drying equipment are model SMC-VMG blowgun and RG881-4 hot air drying chamber.

[0033] The following description, in conjunction with the preferred embodiment one, illustrates the content involved in the above embodiments: This method addresses the residual powder particles inside powder additive manufacturing parts, especially those with complex internal structures and flow channels. It achieves precise cleaning of the parts through a three-step process: pretreatment, pulse cleaning, and post-treatment. The specific steps for cleaning the parts are as follows: Preprocessing stage To address the issues of easy clogging of microchannels and adhesion of metal particles to the inner wall, a process of alternating penetration (or ultrasonic vibration) with low-foaming, high-temperature cleaning agents is adopted.

[0034] The process employs alternating low-foaming and high-temperature penetration, using a low-foaming neutral cleaning agent to prevent air bubbles from stagnating in the microchannels and causing uneven penetration. This is achieved by alternating between slow filling of the channels with static penetration and enhanced contact between the cleaning agent and particles through circulation. At 60–80 °C, the chelating agent in the cleaning agent can quickly penetrate to the adhesion layer between the semi-molten particles and the wall surface, softening metal oxides and reducing adhesion. Ultrasonic vibration at 25–35 kHz generates minute shear forces at the particle-matrix interface, forming micro-cracks that create conditions for particle peeling in the subsequent main cleaning stage.

[0035] Using low-pressure clean air of 0.3~0.6 MPa, the low-pressure airflow can gradually push loose particles out of the flow channel, avoiding particle bridging caused by continuous high pressure; at the same time, the flow rate monitoring can determine whether the flow channel is blocked in real time, and reverse purging is required during the use of airflow to ensure that the flow channel is unobstructed.

[0036] Main cleaning phase Compressed air is filtered in two stages: the first stage uses a 5 μm filter to remove large particles, and the second stage uses a 1 μm filter to remove fine impurities. The pressure dew point is controlled at ≤-20 ℃ by a refrigerated dryer. Place the pre-treated parts on the workbench and fit a flexible self-rotating nozzle with a diameter of 3-4 mm into the inlet of the flow channel. If the nozzle can be inserted, the depth should be 1 / 2 to 2 / 3 of the length of the flow channel; if the orifice is too small, the nozzle should be fitted close to the inlet of the flow channel. Start the gas-liquid pulse generation system and adjust the parameters as follows: Pulse pressure: 1.5~4 MPa (depending on the material, the suitable pressure range is 1.5~2 MPa for aluminum-based / magnesium-based billets, 2.5~3 MPa for titanium-based / nickel-based billets, and 3.5~4 MPa for stainless steel billets); Pulse frequency: 5~20 Hz; Gas-liquid volume ratio: 10:1~30:1; the gas used is compressed air, and the liquid is a low-pressure neutral metal cleaning agent with a cleaning agent concentration of 5%~8% and a pH of 7.5~8.5. During the cleaning process, the nozzle moves synchronously with the workbench. The cleaning port connected to the nozzle is adjusted every 1 to 3 minutes, depending on the area and structure of the part to be cleaned. The total cleaning time is 10 to 15 minutes per part.

[0037] Post-processing stage Use deionized water with a conductivity ≤10 μS / cm to spray for 3 min at a pressure of 0.3 MPa to remove residual cleaning agent; dry with hot air at 65~75 ℃ for 5~15 min to avoid oxidation caused by residual moisture. Samples of the same batch of cleaned parts were tested according to the cleanliness standards for road vehicle parts and systems. The parts were sprayed at a pressure of 0.5 MPa, using a 47 mm / 5 μm filter membrane, and 1 L of cleaning solution. The number of particles per 1000 mm² area was calculated.

[0038] The following description, in conjunction with the preferred embodiment two, illustrates the content related to the above embodiments: Aluminum alloy valve body parts, internally containing staggered aperture flow channels, proportional valve flow channel inner cavity as shown in the attached figure. Figure 2 As shown, the part parameters are aluminum alloy billet produced by laser powder bed fusion additive manufacturing. The main channel is a coarse-diameter horizontal hole with a diameter of 13 mm. The valve sleeve transition section has a 3.5 mm × 4 mm square hole. The internal flow channel section has an alternating variable hole diameter structure with a diameter of 3 mm to 6 mm. The flow channel contains residual semi-molten particles, unmolten particles, and some oil stains. The first stage is pretreatment, involving immersion in an ultrasonic cleaning tank. The cleaning agent is a neutral metal cleaner at 70 ℃, composed of 5% isomeric tridecyl alcohol polyoxyethylene ether, 1.5% aminotrimethylene phosphonic acid, and 0.1% modified silicone oil. The ultrasonic frequency is set at 30 kHz, the temperature at 70 ℃, and the cleaning time is 8 min. After cleaning and drying, clean compressed air is used for gradient pressure purging at a pressure of 0.6 MPa for a total purging time of 3 min to remove some loose particles. The gas-liquid pulse cleaning process is used to fix the nozzle to the main inlet of the flow channel. By adjusting the pressure, frequency and gas-liquid ratio, the diffusion and impact of the fluid itself are used to cover all internal flow channel sections. The pressure is 2.5 MPa, the frequency is 18 Hz, the gas-liquid ratio is 18:1, and the total cleaning time is 6 min. Microbubbles are used to enhance the impact and penetration on narrow flow channels and bifurcation nodes.

[0039] Post-treatment: Clean compressed air was introduced through the main inlet at a pressure of 0.4 MPa for 7.5 minutes. Metallographic images of the flow channel surface before and after cleaning are attached. Figure 3 As shown, the particle removal rate was calculated to be 99.3%, and there was no damage to the internal surface of the blank. Cleanliness was verified using the particle counting method; the largest metal particle size filtered by the filter was 136 μm in length and 96 μm in width, while the total particle count met the standard. (See attached figure.) Figure 4 As shown, this cleaning process achieves good cleaning results.

[0040] The following description, in conjunction with preferred embodiment three, illustrates the content related to the above embodiments: Taking the Corrax stainless steel laser additive servo valve core as an example, the overall diameter is 15 mm, the total length of the valve core is 50 mm, and it contains a Φ1.5 mm deep hole. The implementation steps are as follows: The structural parameters of the part were confirmed. It is made of martensitic precipitated stainless steel with a three-branched internal channel structure. The main hole diameter is 3mm and the diameters of the other three branches are 1.5mm. The internal contaminants are mainly metal particles. During the pretreatment stage, due to the high precision required for the internal deflection rod, ultrasonic pre-cleaning would have an adverse effect on its structure. A neutral metal cleaning agent based on deionized water at 70 ℃ was selected. The cleaning agent composition was 4% isotridecyl polyoxyethylene ether, 2% aminotrimethylene phosphonic acid, and 0.1% modified silicone oil. The parts were immersed in the solution for 20 minutes, dried, and then purged with clean compressed air at 0.8 MPa for 3 minutes to remove some loose particles. Segmented gas-liquid pulse main cleaning: The nozzle is aligned with the main inlet and one branch outlet; Main orifice section: pressure 2.5 MPa, frequency 12 Hz, gas-liquid ratio 20:1, cleaning for 4 min; Branch section: pressure 3.5 MPa, frequency 18 Hz, gas-liquid ratio 22:1, cleaning for 2 min; Fork in the pipeline: pressure 3.5 MPa, frequency 18 Hz, gas-liquid ratio 22:1, cleaning for 2 min; The cleaning fluid is the metal cleaner used in the pretreatment stage; In the post-processing stage, the branch section was purged at a pressure of 0.3 MPa and the main section at a pressure of 0.5 MPa, with each section purged for 2 min; hot air drying at 100 ℃ was carried out for 10 min; and the internal surface characteristics of the parts were detected and their cleanliness level was measured. The test results showed that the particle removal rate was >99% and there was no damage to the internal surface.

[0041] To verify the beneficial effects of the present invention, the following comparative experiment was conducted.

[0042] Comparative Example 1 (Prior Art): Laser-additive stainless steel servo valve core parts, variable orifice flow channel, using high-pressure water jet cleaning process, the part flow channel is a 4 mm to 1.5 mm inverted frustum structure. Fixed cleaning process parameters were used: water pump pressure 15 MPa, cleaning time 3 min, flexible nozzle as close as possible to the cleaning channel, and workpiece not rotated. In the post-processing stage, the cleaned parts are dried with hot air for 10 minutes. Test results and comparison: After cutting the part open, two minor damage dents were found at the 1.5 mm branch opening. Some metal particles with a size of 100 μm were still left at the branch opening. The particle removal was deemed unqualified.

[0043] Comparative Example 2 (Prior Art): Cleaning of stainless steel additive manufacturing hydraulic valve block. Parameters of the part to be cleaned: 316 L stainless steel hydraulic valve block prepared by electron beam melting process, containing cross flow channels (minimum diameter 4 mm), with unmelted stainless steel particles remaining in the flow channels.

[0044] The cleaning process involves directly using gas-liquid pulse cleaning technology, with a 2% sodium carbonate solution as the cleaning agent. The flexible conduit has a diameter of 4 mm and is aligned with each cleaning port on the valve block. The pressure is 3.0 MPa, the pulse frequency is 12 Hz, and the rinsing time is 6 min.

[0045] In the post-treatment stage, the filter was rinsed again with 70℃ deionized water for 3 minutes and dried with hot air at 100℃ for 20 minutes. Test results showed no damage to the flow channel surface and that unmelted metal particles were largely removed. However, many semi-molten metal particles remained on the inner wall of the transfer valve block. After a cleanliness test using 0.8 MPa and 1 L of clean water, and verification using particle counting, the maximum size of the filtered metal particles exceeded the standard, and the total number of particles also exceeded the standard. (See attached image). Figure 5 As shown, the test results obtained by using the gas-liquid pulse cleaning process alone are unqualified.

[0046] As can be seen from the comparison of Examples 2 and 3 with Comparative Examples 1 and 2, the cleaning effect and blank protection effect of the method of the present invention on the staggered variable aperture flow channel are significantly better than high-pressure water cleaning and single gas-liquid pulse cleaning. Moreover, it does not require specific tooling or specific placement of the workpiece, and is more practical for cleaning the inside of parts.

[0047] It should be understood that the terms "one embodiment" or "one example" throughout the specification mean that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the invention. Therefore, "in one embodiment" or "in one example" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Those skilled in the art should also recognize that the embodiments described in the specification are optional embodiments, and the actions and modules involved are not necessarily essential to the invention.

[0048] In various embodiments of the present invention, it should be understood that the sequence number of each process does not necessarily imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0049] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It is particularly important to note that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0050] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A gas-liquid pulse cleaning method of an additively manufactured part, characterized by, The method comprises the following steps: S1, low-pressure soaking pretreatment: fixing and keeping the micro flow channel of the part body to be cleaned, introducing low-foaming neutral metal cleaning agent into the flow channel, and treating by alternating static penetration and circulating flow; then blowing and cleaning the flow channel from one end by low-pressure clean compressed air to remove loose and unfused particles in the flow channel; S2, gas-liquid pulse main cleaning: placing the pretreated part in a gas-liquid pulse cleaning cavity, and making the gas-liquid pulse nozzle aim at at least one inlet / outlet of the flow channel without extending into the flow channel; Starting the gas-liquid pulse generating system, and adjusting the pulse parameters according to the aperture and structural characteristics of the flow channel; S3, targeted post-treatment: first blowing and cleaning the flow channel by compressed air according to the thickness of the flow channel, then drying the part in a hot air circulating oven; and performing targeted detection on the flow channel, and determining that the cleaning is qualified when the particle residual amount of the flow channel is less than a preset threshold value according to the inner wall area of the flow channel.

2. A gas-liquid pulse cleaning method of an additively manufactured part according to claim 1, wherein, In the step S1, The temperature of the low-foaming neutral metal cleaning agent is 60-80 DEG C, the concentration is 3%-5%, and the pH is 7.5-8.5; The time of static penetration and the time of circulating flow are both 1-3 min, and the total soaking time is 6-30 min; The pressure of the low-pressure clean compressed air is 0.4-0.8 MPa.

3. A gas-liquid pulse cleaning method of an additively manufactured part as claimed in claim 1, wherein, In the step S2, The distance between the gas-liquid pulse nozzle and the flow channel port is 5-15 mm, and the nozzle does not need to extend into the flow channel; The flow channel characteristics include aperture change and staggered structure.

4. A gas-liquid pulse cleaning method of an additively manufactured part as claimed in claim 1, wherein, In the step S3, When the compressed air is blown and cleaned in sections, the blowing and cleaning pressure of the thin section is 0.3-0.4 MPa, the blowing and cleaning pressure of the thick section is 0.4-0.5 MPa, and the blowing and cleaning time of each section is 2-3 min; the temperature of the hot air circulating oven is 80-100 DEG C, the air speed is 1-2 m / s, and the drying time is 30-50 min; the cleanliness is evaluated by the flushing method and the particle counting method, the preset threshold value is that the particle residual amount of 5≤X<50 μm particles is not counted, the particle residual amount of 50≤X<100 μm particles is not more than 130, the particle residual amount of 100≤X<150 μm particles is not more than 64, the particle residual amount of 150≤X<200 μm particles is not more than 32, the particle residual amount of 200≤X<400 μm particles is not more than 16, the particle residual amount of 400≤X<600 μm particles is not more than 1, and there is no particle with X≥600 μm.

5. A gas-liquid pulse cleaning method of an additively manufactured part as claimed in claim 1, wherein, In the step S1, The low-foaming neutral metal cleaning agent is composed of 3%-5% isomeric tridecanol polyoxyethylene ether, 1%-2% aminotri(methylene) phosphonic acid, 0.1%-0.3% silicone defoaming agent, and the balance of deionized water.

6. A gas-liquid pulse cleaning method of an additively manufactured part as claimed in claim 1, wherein, In the step S1, The pressure fluctuation of the low-pressure clean compressed air is ≤±0.05 MPa; when the flow rate at the flow channel outlet suddenly decreases by ≥30%, the blowing and cleaning is paused and 0.1 MPa air is introduced in the reverse direction to dredge.

7. A gas-liquid pulse cleaning method of an additively manufactured part as claimed in claim 1, wherein, In the step S1, It also comprises ultrasonic treatment, and the ultrasonic frequency is 25-35 kHz; the 10-100 μm metal particles in the semi-molten state can be weakened in the ultrasonic frequency range.

8. A gas-liquid pulse cleaning method of an additively manufactured part as claimed in claim 1, wherein, In the step S2, The segmental adjustment pulse parameter is specifically: for the fine segment or necked segment with a pore diameter ≤6 mm, pulse pressure 3.5-4 MPa, frequency 15-25 Hz, gas-liquid volume ratio 25-35:1, cleaning time 4-6 min; for the coarse segment or bifurcated segment with a pore diameter >6 mm, pulse pressure 1.5-2 MPa, frequency 5-15 Hz, gas-liquid volume ratio 10-20:1, cleaning time 6-10 min; During the cleaning process, the gas-liquid ratio is switched every 3-5 min, and the gas-liquid ratio switching control is within 20% of the proportion difference; at the same time, 0.1%-0.3% of the degradable micro-bubble generating agent is added to the cleaning liquid.

9. A gas-liquid pulse cleaning method of an additively manufactured part as claimed in claim 1, wherein, In the step S2: The gas-liquid pulse generating system can realize independent or linkage adjustment of pulse pressure 1.5-4 MPa, frequency 5-25 Hz, and gas-liquid ratio 10-35:1, and the adjustment response time is ≤10 ms; the liquid of the gas-liquid pulse is a low-foaming neutral metal cleaning agent filtered by 5 μm precision.

10. A gas-liquid pulse cleaning apparatus for additive manufacturing of a part, characterized in that, It comprises a part fixing mechanism, a pretreatment module, a gas-liquid pulse main cleaning module, and a post-treatment module. The part fixing mechanism is used for fixing the powder additive part blank to be cleaned. The pretreatment module comprises a cleaning agent supply assembly and a low-pressure blowing assembly, the cleaning agent supply assembly is used for introducing a low-foaming neutral metal cleaning agent into the flow channel, and can realize the alternative operation of standing penetration and circulating flow; the low-pressure blowing assembly is used for introducing clean compressed air into the flow channel to remove loose unfused particles in the flow channel; The gas-liquid pulse main cleaning module comprises a gas-liquid pulse cleaning cavity, a gas-liquid pulse nozzle, and a gas-liquid pulse generating system; The gas-liquid pulse cleaning cavity is used for containing the pretreated part; The gas-liquid pulse nozzle is arranged in the cleaning cavity and can be aligned with at least one inlet or outlet of the flow channel; the gas-liquid pulse generating system is connected with the gas-liquid pulse nozzle and can adjust the pulse parameter according to the flow channel characteristics; The post-treatment module comprises a segmented blowing assembly, a hot air drying assembly, and a detection assembly; the segmented blowing assembly is used for introducing compressed air into the flow channel in segments; The hot air drying assembly is used for drying the cleaned part; the detection assembly is used for targeted detection of each flow channel segment to determine whether the particle residue in the flow channel meets the qualified standard.

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