Quality detection method for soldered joint of double-component attitude and orbit control engine injector

Abstract

The invention provides a two-component attitude and orbit control engine injector brazed joint quality detection method, and solves the problems that the quality of an existing injector brazed joint adopts a single airtight test, a brazed seam cannot be visually detected, and a visual image does not have a criterion. According to the method, cleanliness detection, strength test, airtight test, helium mass spectrum leak detection, industrial CT detection and batch extraction product sectioning metallographic inspection are carried out on the injector in sequence, so that the quality of the brazed joint can be effectively examined, and the product production quality control effect is greatly improved; the filling form of the brazing filler metal groove and the flowing state of the brazing filler metal in the brazing seam are observed through industrial CT three-dimensional structure scanning imaging, and correlation between a CT image and the quality of a brazed joint is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of manufacturing a bipropellant attitude and orbit control engine for a spacecraft, and in particular to a method for quality detection of a brazed joint of an injector of a bipropellant attitude and orbit control engine. Background Art

[0002] Brazing is a widely used welding method for injectors, key components of bipropellant attitude and orbit control liquid rocket engines used in spacecraft. Injectors are usually composed of injector frames, injector cores, valve mounting supports, pressure measuring nozzles and other parts. The brazing material melted at high temperature flows into the preset gaps between different parts under the action of capillary force to achieve metallurgical connection.

[0003] In engineering practice, traditional quality inspections for injector brazed joints rely on a single airtightness test method. Injectors are relatively thick, with thin brazing seams, and various parts have different fits, including clearance and interference fits. Conventional X-ray nondestructive testing methods lack appropriate qualification criteria due to equipment sensitivity limitations. Injectors must operate reliably under complex forces, heat, vibration, and shock environments, making the reliability of their welded joints crucial. During testing, it is also necessary to prevent unwanted debris from entering the cavity and clogging the injector orifice. Therefore, a standardized set of testing methods is urgently needed to control injector product quality and ensure safe on-orbit operation of the engine. Summary of the Invention

[0004] In view of the defects in the prior art, the purpose of the present invention is to provide a method for detecting the quality of the brazing joints of the injectors of a bipropellant attitude and trajectory control engine.

[0005] According to the present invention, a method for detecting the quality of a brazed joint of an injector of a bipropellant attitude and trajectory control engine is provided, comprising:

[0006] Step 1: Perform cleanliness test on the injector;

[0007] Step 2: Perform a strength test on the injector. Fill the injector with nitrogen to a first pressure through the tooling and maintain it for a preset time. If the brazed joint is damaged or deformed, it is considered unqualified.

[0008] Step 3: Perform an airtight test on the injector. Fill the injector with nitrogen to a second pressure through the tooling. Immerse the injector in anhydrous ethanol for a preset time. If bubbles are found in the brazed joint, the brazed joint is considered unqualified.

[0009] Step 4: Perform a helium mass spectrometry leak test on the injector. Fill the injector cavity with helium to the third pressure through the tooling. Use a helium mass spectrometry leak detector to sniff the injector. If the total leakage rate is greater than the preset value, the brazed joint is considered unqualified.

[0010] Step 5: Use industrial CT to perform a full structural scan of the injector and perform 3D imaging. Observe the shape of the injector solder groove and the cross section perpendicular to the brazing seam. If the solder grooves on both sides are crescent-shaped and the solder fails to form a complete closed bright ring in the cross section perpendicular to the brazing seam, the brazed joint is considered unqualified.

[0011] Step 6: For each batch of products, randomly select injectors as identification parts according to a preset ratio, repeat step 2 multiple times, and then test according to steps 3 to 5. If the test results are all qualified, the injectors are cross-sectioned and metallographically inspected, the length of the solder flowing in each brazing seam is measured, and the brazing penetration rate of each brazing seam is calculated. If the brazing penetration rate of each brazing seam meets the process requirements, the entire batch of products is considered to have passed the random inspection. Otherwise, check for problems and reassemble the entire batch of products, and return to step 1 until they pass the test; the brazing penetration rate is defined as the length of the solder flowing in the brazing seam divided by the designed length of the brazing seam.

[0012] Furthermore, the cross-sectional geometry of the solder groove of the injector not coated with solder is rectangular.

[0013] Furthermore, step 1 includes:

[0014] A particle counter is used to test the cleanliness of nitrogen and helium entering the inner cavity of the injector. Particles larger than 10μm are not allowed. Before each use of gas, clean the pipeline connected to the injector and block the pipeline outlet connected to the product with a dust-free cloth. Discharge at a pressure of 0.3-0.5MPa gauge pressure for 1 minute. If there is no visible yellow spot, oil stain or excess material on the dust-free cloth, the cleanliness test is qualified. If the cleanliness test fails, check and clean the gas source and pipeline, and test again until the cleanliness test is qualified.

[0015] Furthermore, in steps 2 to 4, air is ventilated from the injector inlet and the outlet is sealed with a tooling.

[0016] Furthermore, in step 5, when the industrial CT is used to perform a full-structure scan of the injector, the pixel size is ≤0.2mm, the operating voltage of the X-ray machine is 180-220V, the scanning parameter integration time is 300-600ms, and the number of projections is ≥1260; when the outer contour diameter of the injector in the direction of irradiation is greater than L, a small focus X-ray machine is used; when the outer contour diameter of the injector in the direction of irradiation is ≤L, a micro focus X-ray machine is used, L=50mm.

[0017] Furthermore, in step 5, when the solder grooves on both sides of the injector are in a full flow shape or a rounded rectangular shape, the injector brazing joint is considered qualified.

[0018] Furthermore, in step 6, the extraction ratio is calculated by rounding up to the nearest integer.

[0019] Furthermore, in step 6, when measuring the length of the solder flowing in the solder joint, the defective length in the solder joint is removed.

[0020] Furthermore, the first pressure is 2P, the second pressure is 1.5P, and the third pressure is 1.5P, where P is the rated working pressure at the injector inlet.

[0021] Furthermore, in step 4, the preset value corresponding to the total leakage rate is 5×10 -6 Pa·m 3 / s.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention effectively assesses the quality of brazed joints by sequentially testing the injector for cleanliness, strength, airtightness, helium mass spectrometry, leak detection, industrial CT, and metallographic examination of batch product sections. Industrial CT allows for visual observation of the brazed joints and assessment of brazing quality based on the images, significantly improving production quality control by applying industrial CT to injector brazing quality testing.

[0024] The present invention focuses on the brazing structure and solder flow characteristics of the dual-component attitude and rail control engine injector, observes the filling form of the solder groove and the solder flow state in the solder joint through industrial CT three-dimensional structural scanning imaging, and realizes the correlation between CT images and the quality of the brazing joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0026] Figure 1 This is a CT inspection image of the brazing tank of a failed brazing joint of a bipropellant attitude and trajectory control engine injector;

[0027] Figure 2 This is a CT inspection image of the brazing seam cross section of a failed brazing joint of a bipropellant attitude and trajectory control engine injector.

[0028] Figure 3 This is a metallographic inspection diagram of the brazing groove after sectioning the unqualified brazing joint of the bi-propellant attitude and trajectory control engine injector;

[0029] Figure 4 This is a CT inspection image of the brazing tank of a qualified brazed joint of a bipropellant attitude and trajectory control engine injector;

[0030] Figure 5 This is a CT inspection image of the brazing seam cross section of a qualified brazed joint of a bipropellant attitude and orbit control engine injector;

[0031] Figure 6This is a flow chart of the quality inspection method for the brazing joints of the injectors of the bi-component attitude and trajectory control engine of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0033] Example 1

[0034] Figure 1 Shown is a CT scan of the solder bath of a failed brazed joint on a bipropellant attitude and orbit control engine injector. Under X-ray illumination, different locations appear different colors due to varying densities. The solder baths on both sides of the image are distinctly crescent-shaped. The black area within the crescent is devoid of solder, while the surrounding bright area represents solder that failed to escape the bath. Above the bath is the gap between the two parts, known as the braze seam, which is 3mm long. The interfering section above the seam and below the bath represents the interference fit between the two parts.

[0035] Figure 2 The figure shows the cross-sectional CT image of the brazing seam of the brazed joint. There is no bright solder in the brazing seam, and an effective sealing joint cannot be formed between the two parts. Figure 3 The following is a metallographic inspection diagram of the brazing groove after the brazing joint is cut. Figure 1 The brazing groove on the right side corresponds to the center. After sectioning and metallographic examination of numerous test specimens, it was found that a bilateral crescent-shaped solder groove can only be formed when the solder completely does not flow out of the groove. However, due to factors such as the sensitivity of the CT inspection equipment, the thickness of the product itself, and the brazing structure, when imaging quality is poor, it can be difficult to accurately determine the crescent shape of the solder groove. Incorporating the flow of solder in the brazing seam can effectively avoid misjudging the quality of the brazed joint.

[0036] Example 2

[0037] Figure 4 This is a CT inspection image of the brazing tank of a qualified brazed joint of a bipropellant attitude and trajectory control engine injector. Figure 5 The following is a CT scan of the brazing seam cross section of the brazed joint. The solder grooves on both sides are full of solder, and a complete and closed bright ring of solder is formed in the brazing seam, indicating that an effective brazing joint has been formed between the two parts.

[0038] like Figure 6As shown, in combination with the brazing structure and brazing material flow characteristics of a bipropellant attitude and rail control engine injector, the present invention proposes a method for detecting the quality of a bipropellant attitude and rail control engine injector brazing joint, comprising the following steps:

[0039] Step 1: Perform cleanliness test.

[0040] A particle counter is used to test the cleanliness of nitrogen and helium entering the inner cavity of the injector. There are no particles larger than 10μm. Before each use of gas, the pipeline connected to the injector is cleaned, and the outlet of the pipeline connected to the product is blocked with a dust-free cloth. The gas is discharged at a pressure of 0.3-0.5MPa gauge pressure for 1 minute. The dust-free cloth is visually checked for visible yellow spots, oil stains, and excess matter. The cleanliness test is qualified.

[0041] Step 2: Perform strength test.

[0042] Ventilation was performed from the injector inlet, and the outlet was sealed with a tooling. Clean nitrogen was slowly filled into the injector through the tooling to a pressure of 2P and maintained for 5 minutes. The products of Example 1 and Example 2 of the present invention had no damage or visible deformation, and the brazing joints were considered qualified; P was the rated working pressure of the injector inlet, 1.5 MPa; the interference fit between the two parts of Example 1 of the present invention formed a hard-sealed false weld.

[0043] Step 3: Perform an airtight test.

[0044] Ventilate from the injector inlet, seal the outlet with a tool, slowly fill the injector with clean nitrogen through the tool to a pressure of 1.5 MPa, and immerse the injector in anhydrous ethanol for 5 minutes. No bubbles are visible to the naked eye in Examples 1 and 2 of the present invention, and the brazed joints are considered qualified.

[0045] Step 4: Perform a helium mass spectrometer leak test.

[0046] Ventilate the injector inlet and seal the outlet with a tool. Slowly fill the injector cavity with clean helium through the tool to a pressure of 1.5 MPa. Use a helium mass spectrometer leak detector to check the entire injector. The total leakage rate of Example 1 and Example 2 of the present invention is no more than 5×10 -6 Pa·m 3 / s, the brazed joint is considered qualified.

[0047] Step 5: Use industrial CT to perform a full structural scan of the injector and perform 3D imaging. The pixel size is ≤ 0.2 mm, the X-ray machine operating voltage is 180-220 V, the scan parameter integration time is 300-600 ms, and the number of projections is ≥ 1260. If the injector's outer diameter in the irradiation direction is greater than L, a small-focus X-ray machine is used. If the injector's outer diameter in the irradiation direction is ≤ L, a micro-focus X-ray machine is used, with L = 50 mm. In this embodiment, the pixel size is 0.2 mm, the X-ray machine operating voltage is 220 V, the scan parameter integration time is 600 ms, and the number of projections is 1400. If the injector's outer diameter in the irradiation direction is 100 mm, a small-focus X-ray machine is used.

[0048] The shape of the injector solder groove and the cross section perpendicular to the brazing seam were observed. The solder grooves on both sides of Example 1 of the present invention were both crescent-shaped, and the solder failed to form a complete and closed bright ring in the cross section perpendicular to the brazing seam. The injector brazing joint was considered unqualified. The solder grooves on both sides of Example 2 of the present invention were full-flow, and the solder formed a complete and closed bright ring in the cross section perpendicular to the brazing seam. The injector brazing joint was considered qualified.

[0049] Step 6: This batch of products produced a total of 30 pieces. Based on a 3% sampling ratio, the calculated value is 0.9. Using the rounding-up method, round one to the nearest integer, randomly select one injector as an inspection piece. Repeat the strength test according to step 2 three times, then perform the test according to steps 3 through 5. If all test results are satisfactory, cross-section the injector and conduct a metallographic examination. Measure the length of the solder flow within the four solder joints, and calculate the penetration rate for each joint. All are above 95%, meeting the process requirements, and the entire batch of products is considered qualified. The penetration rate is defined as the length of the solder flow within the solder joint divided by the designed length of the solder joint. When measuring the length of the solder flow within the solder joint, any defects such as gaps and holes in the solder joint should be excluded.

[0050] The cross-sectional geometry of the solder groove of the injector without solder coating is rectangular.

[0051] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0052] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A method for detecting the quality of a brazed joint of a bipropellant attitude and trajectory control engine injector, characterized in that: include: Step 1: Perform cleanliness test on the injector; Step 2: Perform a strength test on the injector. Fill the injector with nitrogen to a first pressure through the tooling and maintain it for a preset time. If the brazed joint is damaged or deformed, it is considered unqualified. Step 3: Perform an airtight test on the injector. Fill the injector with nitrogen to a second pressure through the tooling. Immerse the injector in anhydrous ethanol for a preset time. If bubbles are found in the brazed joint, the brazed joint is considered unqualified. Step 4: Perform a helium mass spectrometry leak test on the injector. Fill the injector cavity with helium to the third pressure through the tooling. Use a helium mass spectrometry leak detector to sniff the injector. If the total leakage rate is greater than the preset value, the brazed joint is considered unqualified. Step 5: Use industrial CT to perform a full structural scan of the injector and perform 3D imaging. Observe the shape of the injector solder groove and the cross section perpendicular to the brazing seam. If the solder grooves on both sides are crescent-shaped and the solder fails to form a complete closed bright ring in the cross section perpendicular to the brazing seam, the brazed joint is considered unqualified. Step 6: For each batch of products, randomly select injectors as identification parts according to a preset ratio, repeat step 2 multiple times, and then test according to steps 3 to 5. If the test results are all qualified, the injectors are cross-sectioned and metallographically inspected, the length of the solder flowing in each brazing seam is measured, and the brazing penetration rate of each brazing seam is calculated. If the brazing penetration rate of each brazing seam meets the process requirements, the entire batch of products is considered to have passed the random inspection. Otherwise, check for problems and reassemble the entire batch of products, and return to step 1 until they pass the test; the brazing penetration rate is defined as the length of the solder flowing in the brazing seam divided by the designed length of the brazing seam.

2. The method for detecting the quality of the brazing joint of the injector of the bipropellant attitude and trajectory control engine according to claim 1 is characterized in that: The cross-sectional geometry of the solder groove of the injector without solder coating is rectangular.

3. The method for detecting the quality of the injector brazing joint of a bipropellant attitude and trajectory control engine according to claim 1, wherein: Step 1 includes: A particle counter is used to test the cleanliness of nitrogen and helium entering the inner cavity of the injector. Particles larger than 10μm are not allowed. Before each use of gas, clean the pipeline connected to the injector and block the pipeline outlet connected to the product with a dust-free cloth. Discharge at a pressure of 0.3-0.5MPa gauge pressure for 1 minute. If there is no visible yellow spot, oil stain or excess material on the dust-free cloth, the cleanliness test is qualified. If the cleanliness test fails, check and clean the gas source and pipeline, and test again until the cleanliness test is qualified.

4. The method for detecting the quality of the injector brazing joint of a bipropellant attitude and trajectory control engine according to claim 1, wherein: In steps 2 to 4, ventilation is carried out from the injector inlet and the outlet is sealed with a tooling.

5. The method for detecting the quality of the injector brazing joint of the bipropellant attitude and trajectory control engine according to claim 1, characterized in that: In step 5, when industrial CT is used to perform a full-structure scan of the injector, the pixel size is ≤0.2mm, the operating voltage of the X-ray machine is 180-220V, the scanning parameter integration time is 300-600ms, and the number of projections is ≥1260; when the outer contour diameter of the injector in the direction of irradiation is greater than L, a small-focus X-ray machine is used; when the outer contour diameter of the injector in the direction of irradiation is ≤L, a micro-focus X-ray machine is used, and L=50mm.

6. The method for detecting the quality of the injector brazing joint of a bipropellant attitude and trajectory control engine according to claim 1, characterized in that: In step 5, when the solder grooves on both sides of the injector are in a full flow shape or a rounded rectangular shape, the injector brazing joint is considered qualified.

7. The method for detecting the quality of the injector brazing joint of a bipropellant attitude and trajectory control engine according to claim 1, characterized in that: In step 6, the extraction ratio is calculated by rounding up to the nearest integer.

8. The method for detecting the quality of the injector brazing joint of a bipropellant attitude and trajectory control engine according to claim 1, characterized in that: In step 6, when measuring the length of the solder flowing in the solder joint, the defective length in the solder joint is removed.

9. The method for detecting the quality of the injector brazing joint of a bipropellant attitude and trajectory control engine according to claim 1, characterized in that: The first pressure is 2P, the second pressure is 1.5P, and the third pressure is 1.5P, where P is the rated working pressure of the injector inlet.

10. The method for detecting the quality of the brazing joint of the injector of the bipropellant attitude and trajectory control engine according to claim 1, characterized in that: In step 4, the preset value corresponding to the total leakage rate is 5×10 -6 Pa·m 3 / s.

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