Method for repairing cracks of aero-engine combustion chamber casing

Abstract

The invention relates to a crack repairing method for an aero-engine combustion chamber casing. The crack repairing method specifically comprises the steps that S1, cracks are polished; s2, the cartridge receiver is fixed through a welding clamp, and an air outlet in the welding clamp communicates with an exhaust hole in the cartridge receiver; s3, sectional type welding repair welding is conducted on the crack area, and after single-time welding is completed, next-time welding needs to be conducted after the standby box is cooled to the room temperature; and S4, the repair welding on the welded cartridge receiver and the annealing treatment of the air cavity cover are carried out. By means of the method, the deformation size of the inner hole and the bearing hole in the case after welding can be guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of aeroengines, and more particularly to a method for repairing cracks in a combustion chamber casing of an aeroengine. Background Art

[0002] When an aircraft engine combustion chamber casing was returned to the factory for overhaul, it was found that cracks frequently appeared on the same weld, and the crack length was more than 100 mm, accounting for more than 70% of the total length of the weld, which was an ultra-long crack. The combustion chamber casing is an important part with extremely high dimensional accuracy requirements. After the ultra-long cracks were repaired by welding, the welding deformation was large and the size of the parts was difficult to guarantee. The material composition on both sides of the weld is different. The bearing seat side is a carbon steel casting with good material rigidity; the air cavity cover side is austenitic stainless steel with thin wall thickness and poor rigidity. The parts on both sides of the weld have different materials, thicknesses, and rigidities. After repair welding, the internal stress distribution of the parts is uneven. The existing repair process cannot guarantee the size requirements of the inner hole and bearing hole of the casing after the cracks are repaired, and there are safety hazards caused by delayed cracks, which endanger flight safety. It is not suitable for the repair of such cracks in the combustion chamber casing, resulting in the scrapping and replacement of the combustion chamber casing, high repair costs, and long engine repair cycles.

[0003] Prior art CN107971693A discloses a method for repairing cracks in a casing shell of a titanium alloy air intake casing, comprising the following steps: coloring inspection to confirm whether a crack fault occurs in the rear half of the casing shell of the titanium alloy air intake casing; for a casing shell that has cracked, the rear half of the casing shell is circumferentially cut off at a distance of 10 mm from the lower end of the outer cover rib of the casing shell, and the front half of the casing shell is retained; according to the shape and size of the cut rear half of the casing shell, a new casing segment is designed and manufactured, the front end of the new casing segment is provided with a ring-shaped weld lock bottom, the rear installation edge of the new casing segment has a margin, and the new casing segment is provided with a ring-shaped weld lock bottom. A circular reinforcement rib is provided in the middle; the new casing segment is installed together with the retained front half of the casing casing, and they are welded together by electron beam ring welds, and the welds are subjected to color inspection and fluorescence inspection after welding; after confirming that there are no problems with the welding quality, the welded parts are installed on a heat treatment fixture, and a vacuum heat setting method is used to perform a post-weld shape correction heat treatment; after the shape correction heat treatment, the welds are subjected to a color inspection and fluorescence inspection again; the parts after the shape correction heat treatment are subjected to additional mechanical processing, and the weld area, the circular reinforcement ribs, the rear mounting edge and the holes on the rear mounting edge are processed in place, thereby completing the casing casing crack repair work of the titanium alloy air intake casing.

[0004] The technical solution disclosed in the prior art is to cut off the casing shell with cracks, then design reinforcement ribs and weld the cracks to prevent the casing from deforming during the welding process. It is not suitable for this engine, and it cannot guarantee the deformation size of the inner hole and bearing hole on the engine casing after welding. Summary of the invention

[0005] The invention provides a method for repairing cracks in a combustion chamber casing of an aero-engine, which can ensure the deformation sizes of an inner hole and a bearing hole on the casing after welding.

[0006] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0007] A method for repairing cracks in a combustion chamber casing of an aircraft engine is disclosed, which specifically comprises the following steps

[0008] S1: grinding cracks;

[0009] S2: Fix the casing by a welding fixture, and the air outlet on the welding fixture is connected to the exhaust hole on the casing;

[0010] S3: Perform segmented welding on the cracked area, and after a single welding is completed, the next welding should be performed after the casing cools down to room temperature;

[0011] S4: Annealing treatment is performed on the repair welding on the receiver and the air chamber cover after welding.

[0012] Preferably, in step S1, a spherical rotary file is installed on a pneumatic gun to grind the cracks, remove the crack oxide layer, and confirm it by a fluorescent inspection method.

[0013] Preferably, in step S1, the 30 mm area on both sides of the crack is polished at the same time, and the casing is cleaned with an organic solvent.

[0014] Preferably, in step S3, the cracks are repaired by argon arc welding.

[0015] Preferably, in S3, the crack area to be welded is divided into zones, and then the separated zones are welded in sequence, thereby completing segmented welding.

[0016] Preferably, the welding parameters of the argon arc welding are: welding current 55A±5A, argon protection on the front and back sides during the welding process, argon flow rate on the back side 15L / min, and argon flow rate on the front side 8L / min.

[0017] Preferably, in step S4, after the casing crack welding is completed, annealing is performed within 30 minutes.

[0018] Preferably, an oxygen-acetylene flame is used as a heat source, and when heated to a dark red color, that is, 550-650° C., the heated portion is immediately cooled to room temperature with running water to achieve annealing.

[0019] Preferably, the repair method further comprises: S5: inspecting the appearance and sealing performance of the annealed casing.

[0020] Preferably, the sealing inspection is as follows: the combustion chamber casing is immersed in rust-proof water to inspect the sealing of the repair weld and the heat-affected zone, the air pressure is 539±27KPa, and the holding time is 20min.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. Fix the casing with a welding fixture, and connect the air outlet on the welding fixture with the exhaust hole on the casing to facilitate exhaust during welding. At the same time, perform intermittent welding on the cracked area in sections to ensure that the deformation size of the inner hole and bearing hole on the casing after welding is within the control range.

[0023] 2. The cracks repaired by this method have good sealing properties and will not have the problem of delayed cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A flow chart of a method for repairing cracks in a combustion chamber casing of an aircraft engine according to the present invention;

[0025] Figure 2 It is a structural schematic diagram of a casing area to be repaired in a method for repairing cracks in a combustion chamber casing of an aircraft engine according to the present invention;

[0026] Figure 3 It is a structural schematic diagram of a welding fixture in a method for repairing cracks in a combustion chamber casing of an aircraft engine according to the present invention;

[0027] Figure 4 The present invention is a structural schematic diagram of the assembly of a welding fixture and a casing in a method for repairing cracks in a combustion chamber casing of an aero-engine according to the present invention.

[0028] Figure 5 The present invention is a schematic diagram of the structure of a local annealing heating component in a method for repairing cracks in a combustion chamber casing of an aircraft engine. DETAILED DESCRIPTION

[0029] In order to clearly illustrate the technical features of the present solution, the present invention is described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0030] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0031] In addition, in the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying 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 the present application. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0032] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0033] In the present application, unless otherwise clearly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0034] Example 1

[0035] like Figures 1-2 As shown, a method for repairing cracks in a combustion chamber casing of an aircraft engine is disclosed, which specifically comprises the following steps:

[0036] S1: grinding crack 3;

[0037] S2: Fix the casing by welding fixture 4, and the air outlet 6 on the welding fixture 4 is connected with the exhaust hole 7 on the casing;

[0038] S3: Perform segmented welding on the cracked area, and after a single welding is completed, the next welding should be performed after the casing cools down to room temperature;

[0039] S4: Annealing treatment is performed on the repair welding on the casing and the air chamber cover 2 after the welding is completed.

[0040] like Figure 1 As shown, the crack 3 is located between the air chamber cover 2 and the bearing seat 1 of the casing. Before the crack 3 is repaired by sewing, the surface of the crack 3 needs to be polished and repaired first. Specifically, a spherical rotary file installed with an air gun can be used to polish the oxide layer and foreign matter on the surface of the crack 3. After the crack 3 is polished, it is checked by fluorescence to determine that the surface of the crack 3 has been polished. The surface of the crack 3 is made smooth by polishing, ensuring the flatness and uniformity during the subsequent repair of the crack 3. In order to further improve the repair of the crack 3, during polishing, the 30mm area on both sides of the crack 3 is polished, and the casing is cleaned with an organic solvent.

[0041] The polished casing is fixed by a welding fixture 4. The welding fixture 4 is specifically connected to the end of the bearing hole E on the casing, specifically, the welding fixture 4 is fixedly connected to the bolt positioning hole on the casing by bolts. When the casing is fixed to the welding fixture 4, the air outlet 6 on the welding fixture 4 is connected to the exhaust hole 7 on the casing.

[0042] like Figures 3-4 As shown, Figure 4 The middle arrow indicates the direction of gas flow. The welding fixture 4 is annular, and is provided with a mounting hole 9 connected to the casing. An arc-shaped groove is provided on the end of the welding fixture 4 that contacts the casing, and the arc-shaped groove serves as a gas collection groove 5 during welding. The welding fixture 4 is also provided with a gas outlet 6, and the gas outlet 6 is connected to the gas collection groove 5. When the welding fixture 4 is fixed to the casing, the gas outlet 6 is connected to the exhaust hole 7 on the casing through the gas collection groove 5.

[0043] Ventilation protection process:

[0044] High-purity argon gas continuously enters the air cavity 8 from the air inlet 10, filling the entire air cavity 8. During the welding process, the exhaust gas enters the air collecting groove 5 from the exhaust hole 7, and then is discharged from the outlet 6, forming a one-way argon gas circulation protection system.

[0045] The gas collecting groove 5 mainly collects the high-temperature waste gas flowing from the exhaust hole 7 and discharges it from the outlet 6. The outlet 6 is designed to be relatively small, and its function is to adjust the argon pressure in the air cavity so that the argon can be kept in the air cavity 8 and will not escape immediately, thereby losing the argon protection effect; at the same time, it can ensure that fresh argon flows continuously to the back of the weld, and the waste gas generated by welding is discharged from the outlet 6 in time, forming a one-way argon circulation protection system. In addition, part of the welding heat can be taken away by the high-temperature waste gas, which can reduce the welding deformation of the inner hole F and the bearing hole E.

[0046] The crack area is divided into four sections for easy understanding. The four sections are defined as A, B, C, and D. First, the crack in section A is welded, and specifically, crack 3 is repaired by argon arc welding. After the welding of section A is completed, wait for the casing to cool to room temperature before welding one of the remaining three sections of the crack area, and then complete the repair of crack 3 in sequence.

[0047] After the welding is completed, the casing is subjected to local annealing treatment, and finally the complete crack 3 is completely repaired. If the casing is directly annealed as a whole, it is easy to cause the size deformation of other parts of the casing due to thermal stress. Therefore, in this embodiment, after the crack is completely repaired by welding, only the repair welding and the air cavity cover 2 are locally annealed, so as to eliminate the welding stress generated by this repair welding.

[0048] like Figure 5 As shown, the welding fixture is not removed during the whole process of local stress relief annealing, and the welding fixture is removed after the parts are cooled. The heat source uses an oxygen-acetylene flame. When heated to dark red (i.e. 550-650°C), the heated part is immediately cooled to room temperature with running water. The oxygen-acetylene flame heating part is the repair weld and one side of the air cavity cover 2, avoiding the flame directly heating the bearing seat, which can effectively prevent the bearing seat from being deformed due to excessive heat. The length of the repair welding heating range c exceeds the two ends of the repair weld by 10mm; the width d of the heating range d of the air cavity cover 2 is 40-50mm, and e is the weld area.

[0049] In this embodiment, the casing is fixed by a welding fixture 4, and the gas outlet 6 on the welding fixture 4 is connected to the exhaust hole 7 on the casing, so as to facilitate exhaust during welding. At the same time, the heat energy of the welding area is taken away by the exhaust gas, reducing the influence of thermal stress on the inner hole F and the bearing hole E. At the same time, the crack area is intermittently welded in sections, so as to ensure that the deformation size of the inner hole F and the bearing hole E on the casing after welding is within the control range.

[0050] Example 2

[0051] A method for repairing cracks in a combustion chamber casing of an aircraft engine is disclosed, which specifically comprises the following steps:

[0052] S1: grinding crack 3;

[0053] S2: Fix the casing by welding fixture 4, and the air outlet 6 on the welding fixture 4 is connected with the exhaust hole 7 on the casing;

[0054] S3: Perform segmented welding on the cracked area, and after a single welding is completed, the next welding should be performed after the casing cools down to room temperature;

[0055] S4: Annealing treatment is performed on the repair welding on the casing and the air chamber cover 2 after the welding is completed.

[0056] The difference between this embodiment and embodiment 1 is that when welding different crack areas, the separated areas are welded in sequence, thereby completing segmented welding. For example, after welding the crack area of ​​section A, wait for the casing to cool down, then weld the crack of section C, and then weld the crack of section B and section D in sequence, thereby completing all the repairs of crack 3. Of course, the welding of the four cracks can also be completed in sequence. The range of the welding heat-affected zone is effectively controlled not to expand to the inner hole F and the bearing hole E. Through segmented welding, the influence of thermal stress is effectively reduced, and the deformation size of the inner hole F and the bearing hole E after the crack repair is further guaranteed to be within the qualified range.

[0057] The crack repair welding of the test piece of the present invention was carried out. 24 hours after welding, the weld quality was checked by a magnifying glass and a fluorescent inspection, and no cracks or other defects were found. The 539±27KPa pressure test was carried out and the inspection was qualified without leakage. The maximum deformation of the inner hole F diameter was 0.15mm, and the maximum deformation of the inner diameter of the bearing hole E was 0.04mm, and the size met the design requirements. The engine was tested for 10 hours and the repaired combustion chamber casing had no problems in field use. The repair method of the present invention effectively avoids the scrapping of the combustion chamber casing, reduces the repair cost, and shortens the repair cycle of the engine.

[0058] Specifically, the welding current is 55A±5A, and argon protection is provided on the front and back sides during the welding process. The argon flow rate on the back side is 15L / min, and the argon flow rate on the front side is 8L / min.

[0059] The local stress relief annealing process is completed within 30 minutes after welding. The heat source uses an oxygen-acetylene flame. When heated to dark red (i.e. 550-650°C), the heated part is immediately cooled to room temperature with running water.

[0060] In this embodiment, after the repaired combustion chamber casing is placed for 48 hours, a fluorescent inspection is performed on the repair weld and the heat-affected zone.

[0061] Example 3

[0062] The difference between this embodiment and embodiment 1 is that in order to check the repair quality of crack 3, the modified crack 3 can also be inspected for sealing. Specifically, the repaired combustion chamber casing is immersed in anti-rust water to inspect the sealing of the repair weld and the heat-affected zone, the air pressure is 539±27KPa, and the holding time is 20 minutes.

[0063] Finally, crack 3 is inspected again. If there is no water seepage, it proves that the repair of crack 3 meets the quality requirements.

[0064] Obviously, the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for repairing cracks in a combustion chamber casing of an aircraft engine, characterized in that: The specific steps include: S1: grinding cracks; S2: Fix the casing by a welding fixture, and the air outlet on the welding fixture is connected to the exhaust hole on the casing; S3: Perform segmented welding on the cracked area, and after a single welding is completed, the next welding should be performed after the casing cools down to room temperature; S4: Annealing treatment is performed on the repair welding on the receiver and the air chamber cover after welding.

2. The method for repairing cracks in a combustion chamber casing of an aircraft engine according to claim 1, characterized in that: In the step S1, a spherical rotary file is installed with an air gun to grind the crack, remove the crack oxide layer, and confirm it by using a fluorescent inspection method.

3. The method for repairing cracks in a combustion chamber casing of an aircraft engine according to claim 2, characterized in that: In the step S1, the 30 mm area on both sides of the crack is polished at the same time, and the casing is cleaned with an organic solvent.

4. The method for repairing cracks in a combustion chamber casing of an aircraft engine according to claim 1, characterized in that: In the step S3, the cracks are repaired by argon arc welding.

5. The method for repairing cracks in a combustion chamber casing of an aircraft engine according to claim 4, characterized in that: In S3, the crack area to be welded is divided into sections, and then the separated areas are welded in sequence, thereby completing the segmented welding.

6. The method for repairing cracks in a combustion chamber casing of an aircraft engine according to claim 4, characterized in that: The welding parameters of the argon arc welding are: welding current 55A±5A, argon protection on the front and back sides during the welding process, argon flow rate on the back side 15L / min, and argon flow rate on the front side 8L / min.

7. The method for repairing cracks in a combustion chamber casing of an aircraft engine according to claim 1, characterized in that: In step S4, after the casing crack repair welding is completed, the repair welding and the air cavity cover are annealed within 30 minutes.

8. The method for repairing cracks in a combustion chamber casing of an aircraft engine according to claim 7, characterized in that: Using oxygen-acetylene flame as heat source, heat to dark red, i.e. 550-650°C, and immediately cool the heated part to room temperature with running water to achieve annealing.

9. The method for repairing cracks in a combustion chamber casing of an aircraft engine according to claim 1, characterized in that: The repair method further includes: S5: inspecting the appearance and sealing performance of the annealed casing.

10. The method for repairing cracks in a combustion chamber casing of an aircraft engine according to claim 9, characterized in that: The sealing inspection is as follows: the combustion chamber casing is immersed in anti-rust water to inspect the sealing of the repair weld and the heat-affected zone, the air pressure is 539±27KPa, and the holding time is 20min.

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