A mold box testing method for engine internal flow channel welds

Abstract

The present invention relates to a mold box testing method for engine inner flow channel welds, including the process of preparing a mold box, pressure testing, strength calculation and tissue analysis, and judging whether the inner flow channel welds of an aerospace engine meet the requirements. The mold box is divided into an upper plate and a lower plate. The upper side of the lower plate is provided with ribs, straight grooves, connecting grooves, and water holes. The layer plate material and brazing process are the same as the material and brazing process used for the inner flow channel welds of the engine being tested. Compared with traditional evaluation methods, the mold box testing method of the present invention not only reflects the quality of the brazing joint, but also reflects the success rate of multi-pass brazing of the double-layer inner flow channel structure. It is a coupled reflection of the weld strength and the rib-layer welding rate, uniformly evaluates the structural strength, accurately reflects the internal strength of the welding process, and realizes an overall evaluation of the welding quality of the aerospace engine. At the same time, it greatly saves the testing cost and shortens the testing cycle, which is of great significance to promoting the design and production of aerospace engines and evaluating service reliability.

Description

Technical Field

[0001] The present invention belongs to the technical field of aerospace engines, and in particular relates to a mold box testing method for engine inner flow channel welds, which is suitable for engine thrust chamber welding quality detection and evaluation. Background Art

[0002] During their service, aerospace engines operate in an environment characterized by high temperatures, high pressures, and vibrations. These factors place stringent demands on the high-temperature mechanical properties and fatigue resistance of their structures and components. To control overall mass and enhance heat dissipation and combustion efficiency, aerospace engine thrust chambers typically employ a double-layer structure. While reducing weight, internal flow channels are used to inject liquid oxidizers (such as liquid oxygen and N2O4) and fuels (such as liquid hydrogen, kerosene, and UDMH) into the engine body and tail nozzle. This allows for rapid engine cooling while preheating the fuel and oxidizer, improving combustion efficiency. The quality of the double-layered internal flow channel structure of aerospace engines is directly related to the reliability and safety of rockets and spacecraft in service. Therefore, quality inspection of this internal flow channel structure is of vital importance to the aerospace industry.

[0003] The strength of an aerospace engine's internal flow path structure primarily comes from the structural strength between its double-layered panels and the ribs. Currently, the production of double-layered internal flow path structures primarily involves brazing the engine's outer shell and the ribbed inner wall. The welded joints between the rib ends and the engine's outer wall are the most vulnerable components of the overall structure. Engine failures caused by pressure or flow path blockage often manifest themselves as failures in the brazed seams between the ribs and the outer wall. Therefore, evaluating the strength of these welds is crucial when assessing the quality of an engine's internal flow path structure.

[0004] At present, the strength evaluation of the double-layer structure of aerospace engine bodies mainly relies on pressure testing, simulated tensile testing and metallographic analysis. Among them, the pressure test is to seal the engine body parts after brazing production, and then inject high-pressure water between the layers until the engine fails. The maximum pressure it withstands before failure is the structural strength of its double-layer internal flow channel. Simulated tensile testing can use the same base material as the engine to prepare brazed joints under the same conditions as its brazing production process, and process them into standard tensile specimens for tensile testing. The strength obtained from the tensile test is used as the strength of the weld between the ribs and the outer wall. The metallographic observation method usually directly cuts the cross section of the double-layer wall structure of the engine, prepares the metallographic specimen for observation, and analyzes the defects and interface characteristics such as interface welding rate, holes and precipitates, so as to judge the quality of the joint. However, existing methods have numerous drawbacks. Directly testing the entire engine under pressure requires the use of a finished, welded engine, which is extremely expensive and requires a long testing cycle. Simulated tensile testing results, however, struggle to accurately reflect weld quality and joint strength, and are difficult to accurately reflect the overall weld quality of the engine's numerous welds or the overall bond strength between the two panels. Metallographic analysis struggles to directly provide strength data, serving only as a supplementary indicator of weld strength and similarly relying on the finished engine. Therefore, it is crucial to develop a comprehensive test method for comprehensively testing the bond strength of an engine's two-panel structure. Summary of the Invention

[0005] In order to overcome the shortcoming that the strength test of the aerospace engine body with a double-layer inner flow channel structure is difficult to accurately reflect the overall bonding quality, the present invention proposes a mold box testing method for the engine inner flow channel weld.

[0006] In order to solve the above technical problems, the mold box for the engine inner flow channel weld adopted in the testing method of the present invention includes a layer plate, which is divided into an upper plate and a lower plate.

[0007] The upper plate and the lower plate are opposite to each other up and down.

[0008] The upper plate is a square plate.

[0009] The upper side of the lower plate is provided with ribs and straight grooves, the ribs and straight grooves are arranged at intervals, and the upper side of the ribs is the rib end face.

[0010] The upper side of the lower plate is provided with a connecting groove, the periphery of the lower plate is a side wall, and the upper surface of the side wall is a side wall end face. One of the side walls facing the connecting groove is provided with a water hole, and the water hole is connected to the connecting groove.

[0011] The communicating groove has the same depth as the straight groove, and the communicating groove and the straight groove together constitute the inner space of the mold box, and the water hole is connected to the inner space.

[0012] The rib end faces, the side wall end faces and the bottom surface of the upper plate are connected by brazing with solder.

[0013] The laminate material and brazing process are the same as those used for the flow channel welds in the tested engine.

[0014] In order to solve the above technical problems, the mold box testing method of the present invention includes the following steps:

[0015] Step 1: Prepare the laminate

[0016] The lower plate is prepared by mechanical processing using the same batch of materials of a certain type of tested aerospace engine as the parent material.

[0017] Step 2: Welding the layers

[0018] The same brazing process as that used for welding the inner flow channel of the tested aerospace engine is used to braze the layer plates to obtain a mold box for testing the weld seam of the inner flow channel of the engine.

[0019] Step 3, pressure test

[0020] First, pre-fill water and exhaust into the mold box. The water hole of the mold box is connected to the pressure gauge and high-pressure water pump and placed in a safe protection area.

[0021] Secondly, use a high-pressure water pump to inject water into the mold box through the water hole and pressurize it until the mold box fails, and record the maximum water injection pressure on the pressure gauge.

[0022] Step 4, strength calculation and organization analysis:

[0023] First, the failure strength of the weld is calculated based on the maximum water injection pressure at failure and the mold box structure.

[0024] Secondly, metallographic specimens and fracture specimens of the failed mold box brazing area were prepared, and the metallographic structure and fracture morphology were analyzed.

[0025] Finally, based on the calculated brazing strength and microstructure, and according to the technical indicators of the aerospace engine inner flow channel weld, it is judged whether the aerospace engine inner flow channel weld meets the requirements.

[0026] In the mold box testing method described above, the step 1 of preparing the laminate further comprises:

[0027] First, choose the laminate material

[0028] The laminate material is from the same batch of materials of a certain type of aerospace engine being tested, and the selected laminate material is used as the parent material.

[0029] The shape of the layer material is a square plate with a side length of L, L = 300 to 450 mm. The thickness of the upper plate material is d, d = 15 to 35 mm. The thickness of the lower plate material is D, D = 20 to 40 mm.

[0030] The raw material for the upper plate is the upper plate.

[0031] Secondly, machining the lower plate raw materials

[0032] Use a milling machine or machining center to mill the upper side of the lower plate raw material. Mill evenly distributed straight grooves along the upper side of the lower plate raw material, forming straight ribs between the straight grooves, and mill connecting grooves along the centers of the ribs.

[0033] A water hole is machined on the side wall of one end of the communicating groove, and the water hole corresponds to the center of the one end of the communicating groove.

[0034] The lower plate raw material is machined to obtain the lower plate.

[0035] In the mold box testing method described above, the straight groove has a width of 7 to 10 mm, a depth of 10 to 12 mm, and a rib width of 2 to 5 mm. The connecting groove has the same width and depth as the straight groove. The water hole has a diameter of 8 mm, and the sidewall thickness is greater than the straight groove width.

[0036] In the mold box testing method described above, the step 2 of welding the layer further comprises:

[0037] First, fix the brazing material to the end face of the lower plate rib and the end face of the side wall.

[0038] Secondly, align the upper plate and the lower plate up and down, use the brazing fixture as a fixture to fix the upper plate and the lower plate that fixes the brazing material.

[0039] Finally, brazing.

[0040] A mold box for testing the flow channel weld seam in aerospace engines was obtained.

[0041] In the mold box test method described above, the brazing process is carried out in a vacuum brazing furnace. The brazing fixture, the clamped upper plate, and the lower plate holding the brazing material are placed in the brazing furnace. The brazing process parameters are consistent with the brazing process parameters of the flow channel weld of a certain type of aerospace engine being tested. For example, the brazing vacuum degree is p, p<4×10 -3 The heating rate was 8°C / min, the holding temperature was 1120°C, the holding time was 50 min, and the sample was cooled to room temperature and taken out.

[0042] The beneficial effects of the present invention are:

[0043] A mold box testing method for engine internal flow channel welds uses a mold box pressure test to simulate the engine's double-layer internal flow channel structure, enabling a comprehensive assessment of aerospace engine weld quality. Compared to traditional engine overall pressure tests, this method avoids the long testing cycles and high costs. It also circumvents the difficulty of simulated tensile tests in accurately reflecting the weld strength at the interlaminar ribs. It can provide the overall strength of the brazed structure of a double-layer internal flow channel engine. Furthermore, it allows for large-scale, multi-batch testing, improving testing efficiency, reducing testing costs, and shortening testing cycles, which is of great significance for advancing engine design, production, and testing.

[0044] Compared with the simulated tensile test, the mold box pressure test not only reflects the quality of the brazing joint, but also reflects the overall indicator of the success rate of the brazing quantity. It is a coupled reflection of the weld strength and the rib-laminate welding rate. It conducts a unified assessment of the structural strength and can more accurately reflect the internal strength of the engine laminate structure under the current welding process.

[0045] After completing the pressure test, the mold box can still be cut and prepared for metallographic samples, and the microscopic morphology characteristics of welds with different fracture degrees can be observed and analyzed, and their strength can be supplemented with analysis and explanation. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The present invention will be further described below with reference to the accompanying drawings and examples.

[0047] Figure 1 Schematic diagram of the mold box;

[0048] Figure 2 Schematic diagram of the lower plate;

[0049] Figure 3 It is the top view of the lower plate;

[0050] Figure 4 for Figure 3 AA cross-section diagram.

[0051] In the figure: 1. upper plate; 2. lower plate; 3. rib end face, 4. side wall end face, 5. connecting groove, 6. water hole. DETAILED DESCRIPTION

[0052] Example

[0053] A mold box for the flow channel weld in an engine, comprising a layer plate, such as Figures 1 to 4As shown, the laminate consists of an upper plate 1 and a lower plate 2, which face each other vertically. The upper plate 1 is a square flat plate. The upper side of the lower plate 2 is provided with a connecting groove 5. The perimeter of the lower plate 2 forms a sidewall, the upper surface of which is a sidewall end surface 4. The sidewall is provided with a through-hole 6, which communicates with the connecting groove 5. Ribs and straight grooves are arranged on the upper side of the lower plate 2, with the upper surfaces of the ribs forming rib end surfaces 3. The connecting grooves 5 and the straight grooves are equidistant from the side end surfaces of the lower plate 2, forming the sidewalls with the side end surfaces. The connecting grooves 5 and the straight grooves have the same depth as the straight grooves, and together they define the interior space of the mold box. The water holes 6 are connected to this interior space. The rib end surfaces 3 and the sidewall end surfaces 4 are brazed to the lower surface of the upper plate 1 using brazing filler metal. The laminate material and brazing process are identical to those used for the internal flow channel welds of a certain engine being tested.

[0054] A mold box testing method for engine internal flow channel welds is disclosed. The test mold box is prepared using the same materials and brazing process as the internal flow channel welds of a certain type of aerospace engine being tested. The mold box is subjected to a pressure test, and the strength and metallographic structure of the welds of the failed mold box are analyzed to determine whether the internal flow channel welds of the aerospace engine meet the technical requirements. The specific process includes the following steps:

[0055] Step 1: Prepare the laminate

[0056] First, choose the laminate material

[0057] The laminate material is from the same batch of materials of a certain type of aerospace engine being tested, and the selected laminate material is used as the parent material.

[0058] The parent material is made of stainless steel or high-temperature alloy, and the final state of the material is rolled plate. Specific materials include: stainless steel can be 1Cr18Ni9Ti or 1Cr21Ni5Ti, and high-temperature alloy can be GH5188 or GH3230.

[0059] The shape of the layer material is a square plate with a side length of L, L = 300-450 mm. The thickness of the raw material of the upper plate 1 is d, d = 15-35 mm. The thickness of the raw material of the lower plate 2 is D, D = 20-40 mm.

[0060] The selected upper plate 1 raw material is used as the upper plate 1.

[0061] Obtain the raw materials of lower plate 2 and upper plate 1.

[0062] Secondly, machining the lower plate 2 raw material

[0063] Use a milling machine or machining center to mill the upper side of the lower plate 2 raw material. First, mill uniformly distributed straight grooves along the upper side of the lower plate 2 raw material. The straight groove width is a, a = 7-10 mm, and the straight groove depth is h, h = 10-12 mm. Straight ribs are formed between the straight grooves. The rib width is b, b = 2-5 mm. Connecting grooves 5 are milled along the center of the ribs. The width and depth of the connecting grooves 5 are equal to those of the straight grooves. The straight grooves and the side edges of the lower plate 2 raw material form sidewalls. The distance between the straight grooves and the side edges of the lower plate 2 raw material is the sidewall thickness. The sidewall thickness is greater than the straight groove width and greater than the rib width.

[0064] On the side wall of one end of the connecting groove 5, a water hole 6 is machined. The water hole 6 corresponds to the center of one end of the connecting groove 5. The diameter of the water hole 6 is

[0065] The lower plate 2 raw material is machined to obtain the lower plate 2.

[0066] Step 2: Welding the layers

[0067] First, fix the brazing material to the rib end face 3 and the side wall end face 4 of the lower plate 2;

[0068] Secondly, align the upper plate 1 and the lower plate 2 up and down, and use the brazing fixture as a fixture to fix the upper plate 1 and the lower plate 2 that fixes the brazing material.

[0069] Finally, brazing.

[0070] The brazing process is carried out in a vacuum brazing furnace. The brazing fixture, the clamped upper plate 1, and the lower plate 2 holding the brazing material are placed in the brazing furnace. The brazing process parameters are consistent with the brazing process parameters of the flow channel weld of a certain type of aerospace engine being tested. For example, the brazing vacuum degree is p, p<4×10 -3 The heating rate was 8°C / min, the holding temperature was 1120°C, the holding time was 50 min, and the sample was cooled to room temperature and taken out.

[0071] A mold box for testing the flow channel weld seam in aerospace engines was obtained.

[0072] Step 3, pressure test

[0073] First, water is pre-injected into the mold box and air is exhausted. The water hole 6 of the mold box is connected to the pressure gauge and the high-pressure water pump and sealed and fixed, and then placed in a safety protection area.

[0074] Secondly, use a high-pressure water pump to inject water into the mold box through the water hole 6 and pressurize it until the mold box fails, and record the maximum water injection pressure on the pressure gauge.

[0075] Step 4: Strength calculation and tissue analysis

[0076] First, the failure strength of the weld is calculated based on the maximum water injection pressure at failure and the mold box structure.

[0077] Secondly, metallographic specimens and fracture specimens of the failed mold box brazing area were prepared, and the metallographic structure and fracture morphology were analyzed.

[0078] Finally, based on the calculated brazing strength and microstructure, and according to the technical indicators of the aerospace engine inner flow channel weld, it is judged whether the aerospace engine inner flow channel weld meets the requirements.

[0079] Table 1 Related parameters

[0080]

Claims

1. A mold box testing method for engine internal flow channel welds, characterized in that: The mold box includes a layer plate, which is divided into an upper plate (1) and a lower plate (2); The upper plate (1) and the lower plate (2) are opposed to each other in vertical direction; The upper plate (1) is a square plate; The upper side of the lower plate (2) is provided with ribs and straight grooves, the ribs and straight grooves are arranged at intervals, and the upper side of the ribs is a rib end surface (3); A connecting groove (5) is provided on the upper side of the lower plate (2), the periphery of the lower plate (2) is a side wall, and the upper surface of the side wall is a side wall end face (4); one of the side walls directly facing the connecting groove (5) is provided with a water hole (6), and the water hole (6) is in communication with the connecting groove (5); The communicating groove (5) has the same depth as the straight groove, and the communicating groove (5) and the straight groove together constitute the internal space of the mold box, and the water hole (6) is connected to the internal space; The rib end surface (3), the side wall end surface (4) and the bottom surface of the upper plate (1) are brazed and connected via brazing material; The laminate material and brazing process are the same as those used for the flow channel welds in the tested engine; The straight groove width is a , a =7~10 mm, The straight groove depth is h , h =10~12 mm The rib width is b , b =2~5 mm The width and depth of the connecting groove (5) are equal to those of the straight groove, and the diameter of the water hole (6) is 8 mm , the side wall thickness is greater than the straight groove width; Test methods include: Step 1, prepare the laminate: The lower plate (2) is prepared by machining using the same batch of materials as the tested aerospace engine material as the parent material; Step 2, welding the layers: The same brazing process as that used for welding the flow channel in the aerospace engine being tested is used to braze the laminates to obtain a mold box for testing the weld seam in the flow channel of the engine. Step 3, pressure test: First, pre-fill water and exhaust the mold box, connect the water hole (6) of the mold box to the pressure gauge and high-pressure water pump, and place it in a safety protection area; Secondly, use a high-pressure water pump to inject water into the mold box through the water hole (6) to increase pressure until the mold box fails, and record the maximum water injection pressure on the pressure gauge; Step 4, strength calculation and organization analysis: First, the failure strength of the weld is calculated based on the maximum water injection pressure at failure and the mold box structure; Secondly, metallographic specimens and fracture specimens were prepared at the brazing site of the failed mold box, and the metallographic structure and fracture morphology were analyzed. Finally, based on the calculated brazing strength and microstructure, and according to the technical indicators of the aerospace engine inner flow channel weld, it is judged whether the aerospace engine inner flow channel weld meets the requirements.

2. The mold box testing method for engine inner flow channel weld according to claim 1, characterized in that: The step 1 of preparing the laminate further comprises: First, select the laminate material: The laminate material is from the same batch of materials of a certain type of aerospace engine being tested, and the selected laminate material is used as the parent material; The shape of the laminate material is a square plate with a side length of L , L =300~450 mm ; The thickness of the upper plate (1) material is d , d =15~35 mm ; The thickness of the lower plate (2) material is D , D =20~40 mm ; The raw material for the upper plate (1) is the upper plate (1); Next, machine the lower plate (2) raw material: A milling machine or a machining center is used to mill the upper side of the raw material of the lower plate (2); uniformly distributed straight grooves are milled along the upper side of the raw material of the lower plate (2), straight ribs are formed between the straight grooves, and a connecting groove (5) is milled along the center of the ribs; a water hole (6) is machined on the side wall of one end of the connecting groove (5), and the water hole (6) corresponds to the center of one end of the connecting groove (5); the raw material of the lower plate (2) is machined to obtain the lower plate (2).

3. The mold box testing method for engine inner flow channel weld according to claim 1, characterized in that: The step 2 of welding the layers further comprises: First, the brazing material is fixed to the rib end surface (3) and the side wall end surface (4) of the lower plate (2); Secondly, the upper plate (1) and the lower plate (2) are aligned vertically, and a brazing fixture is used as a fixture to fix the upper plate (1) and the lower plate (2) for fixing the brazing material; Finally, brazing is performed to obtain a mold box for testing the flow channel welds in aerospace engines.

4. The mold box testing method for engine inner flow channel weld according to claim 1, characterized in that: The brazing process is as follows: the brazing tool and the clamped upper plate (1) and the lower plate (2) for fixing the brazing material are placed in the brazing furnace; the brazing process parameters are consistent with the brazing process parameters of the flow channel weld of a certain type of aerospace engine being tested; the brazing vacuum degree is p , p <4×10 -3 Pa; heating rate is 8℃ / min, holding temperature is 1120℃, holding time is 50min, cool to room temperature with the furnace, and take out.

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