CN115625478A - Surfacing repair method for damage of aeroengine pressure sensor shell - Google Patents

Abstract

The invention provides a surfacing repair method for damage of a pressure sensor shell of an aircraft engine, which solves the defects of low repair qualified rate and complex repair process of the existing pressure sensor shell by adopting a shell sleeve replacing method. The method comprises the following steps: 1) pretreatment before welding, 2) surfacing and 3) treatment after welding; by selecting proper welding materials and welding process parameters, welding heat input is accurately controlled, the dissolution, melting and burning loss of wear-resistant tissues in the alloy are prevented, and a high-quality surfacing wear-resistant layer can be obtained.

Description

Surfacing repair method for damage of aeroengine pressure sensor shell

Technical Field

The invention belongs to the technical field of surfacing, and relates to a surfacing repair method for damage of a shell of a pressure sensor of an aircraft engine, in particular to a surfacing repair method for local damage of a nitriding layer on the surface of a sleeve of the pressure sensor of the aircraft engine.

Background

Wear is the primary form of failure of aerospace parts, causing significant losses. The wear of a sleeve of a pressure sensor shell of a certain type of engine is a main failure mode of the part, when the part is manufactured, the sleeve is connected with the pressure sensor shell in a welding mode, the sleeve is made of martensitic stainless steel 1Cr14Ni3W2VB, a nitriding layer is arranged on the surface of the sleeve, the wear-resistant function is achieved (as shown in figure 2), and once the surface of the nitriding layer is damaged, the part can fail.

When the problem of surface damage of a nitriding layer is faced, two modes of repairing a damaged part by a local nitriding method or repairing a pressure sensor shell by replacing a sleeve are generally available. The nitriding process is a process of permeating active nitrogen atoms into the surface layer of the steel part, namely the process of saturating the surface with the nitrogen atoms, the chemical composition and the tissue state of the surface are changed, the nitriding process is to wholly heat the part in a furnace, the pressure sensor shell is a whole part, the nitriding part is only a sleeve part, the non-nitriding part is difficult to effectively protect when the method is adopted for repairing, and the whole heating can influence the use performance of the pressure sensor shell, so that the local nitriding process is difficult to realize for repairing the pressure sensor shell. The traditional repairing method is to repair the pressure sensor shell by replacing the shell sleeve, namely, one end of the pressure sensor shell sleeve is cut off along one side of the original welding line, and then a new sleeve is welded and connected with the other end of the pressure sensor shell, but the welding qualification rate is low in the welding process. Because the casing of the pressure sensor is repaired by adopting a casing replacement mode, the casing needs to be newly selected and manufactured according to the size of the casing of the pressure sensor after cutting, so that the total length of the pressure sensor is ensured to be 364 +/-0.5 mm; and the welding position of the sleeve and the pressure sensor shell is in a 10mm X t2.0mm tubular structure butt welding mode, the outer diameter of the sleeve is 10.0mm, the inner diameter of the sleeve is 6.0mm, X-ray flaw detection and 4.8mm steel ball passing tests are required after welding, 4.8mm steel balls are required to completely pass through under the condition of complete penetration, but the phenomenon that 4.8mm steel balls are difficult to pass through after the welding seam part is incompletely or completely penetrated in the actual welding process often exists, the qualified rate of the pressure sensor shell meeting the use requirement is only 30%, the problems of low repairing qualified rate and poor coaxiality exist, namely the phenomenon that the 4.8mm steel balls are difficult to pass through due to incomplete penetration or complete penetration of the welding seam at the butt joint part of the shell and the sleeve and the phenomenon that the coaxiality of the pressure sensor shell exceeds 0.02 specified by a process file exist, and the repair progress of the aero-engine is seriously influenced.

Therefore, the existing repairing method is complex in process and low in repairing qualified rate, and therefore a repairing method aiming at local damage of a nitriding layer on the surface of a casing sleeve of a pressure sensor of an aircraft engine needs to be researched.

Disclosure of Invention

The invention aims to overcome the defects that the repair of the shell casing of the existing pressure sensor is low in qualification rate and complicated in repair process by adopting a shell casing replacement method, and provides a surfacing repair method for damage of the pressure sensor shell of an aircraft engine.

In order to achieve the above purpose, the invention provides the following technical scheme:

a surfacing repair method for damaged housing of a pressure sensor of an aircraft engine is characterized by comprising the following steps: the method comprises the following steps:

1) Pre-weld pretreatment

Polishing the damaged part of the casing of the pressure sensor until the metal luster is exposed, keeping the surface to be repaired flat and free of defects, and cleaning the polished surface of the casing by using alcohol;

2) Build-up welding

Placing the pressure sensor shell pretreated in the step 1) on a welding workbench to ensure that the damaged part of the sleeve is upward (the rear end of the pressure sensor shell can be cushioned by a cushion block) to facilitate welding, and performing segmented argon arc welding according to the damaged part by adopting a predetermined surfacing material and surfacing process (specific process parameters) to ensure that all surfacing wear-resistant layers are surfaced on the damaged part of the sleeve, and the outer diameter of the surfacing part after surfacing is not less than the required size of the pressure sensor shell sleeve;

the segmented welding is that after one-segment welding is finished, argon is introduced into a welding gun to cool a surfacing part, and then the next segment is surfaced;

the surfacing material and the surfacing process are determined by the following method:

s1, selecting at least two surfacing materials with the hardness close to that of the surface of the original nitriding layer of the casing pipe of the pressure sensor and the wear resistance requirement of the casing pipe of the pressure sensor as alternative repairing materials according to the hardness requirement of the surface of the original nitriding layer of the casing pipe of the pressure sensor and the wear resistance requirement of the casing pipe of the pressure sensor;

s2, determining the surfacing material by comparing the wear volumes of the alternative repairing materials selected in the S1 through a fretting wear test under the same test condition, wherein the smaller the wear volume is, the better the wear resistance is;

s3, setting different process parameters to perform a welding test according to the thickness and damage conditions (namely depth and shape) of the surfacing required by the damaged part of the sleeve until the surfacing part is completely fused and the appearance is free of defects (namely the standard of no defects such as cracks, undercut, air holes and the like) is met by visual observation, and determining a surfacing process; the determined welding process parameters are as follows:

current intensity: 40A to 45A;

the diameter of the tungsten wire is as follows:

inert gas argon was used as shielding gas argon flow: 10L/min to 15L/min;

back argon flow: 4L/min-8L/min;

polarity of power supply: direct current is connected positively;

because manual argon arc welding needs to finely adjust welding parameters by observing the state of a molten pool, the welding quality can be ensured within the process range.

3) Post-weld treatment

And performing finish machining on the surfacing part, recovering the excircle of the sleeve to the original size, processing until the surfacing layer is flush with the original nitriding layer, and finishing damage repair by meeting the design requirement of the pressure sensor shell sleeve, thereby meeting the use requirement.

Further, in the step 1), the pre-welding pretreatment of the workpiece to be surfacing welded refers to polishing the damaged part (irregular damaged part) of the casing of the pressure sensor by using a grinding wheel until the metal luster is exposed, keeping the surface to be repaired flat and free of defects such as pits, sharp corners and burrs, and then cleaning oil stains and sweat stains on the surface of the polished casing by using alcohol.

Further, the pressure sensor shell sleeve is made of martensitic stainless steel 1Cr14Ni3W2VB;

in the step 2), the grade of the selected welding wire is GH40, and the specification is

Further, in the step 3), a universal cylindrical grinder is adopted to carry out finish machining on the surfacing part, the outer circle of the sleeve is recovered to the original size, in order to ensure the coaxiality of the shell of the pressure sensor and not damage the original nitriding layer, a small amount of grinding quantity is 0.1-0.2 mm each time in a mode of multiple times during finish machining, so that the machining deformation is controlled, and the machining stress is reduced.

Further, in the step 2), the outer diameter of the surfacing part after surfacing is not less than

I.e., the desired size of the pressure sensor housing sleeve of a certain type.

Further, in step 3), the surface roughness required by the design of the pressure sensor shell sleeve is 0.8 μm, which is the roughness requirement of a certain product.

Further, in S1, the surface hardness required by the original nitriding layer is not less than 80HV; GH40 and CoCrW materials with better wear resistance and equivalent to the effect of a nitriding layer are selected as surfacing materials, standard ball-disc fretting wear samples are manufactured, fretting wear tests are carried out on the samples in three states (the nitriding layer, the surfacing GH40 and the surfacing CoCrW), and the surfacing materials are determined according to the wear test results.

Further, in S3, the specification of the welding wire is selected to be

The welding process parameters are as follows:

current intensity: 45A;

diameter of tungsten filament:

inert gas argon is used as shielding gas argon flow: 12L/min;

back argon flow: 6L/min;

polarity of power supply: the direct current is connected.

Further, the method also comprises the step 4):

step 4) fluoroscopy

And performing fluorescence inspection on the surfacing part of the machined part to ensure that the outer surface of the surfacing layer of the sleeve has no crack defect.

A repaired aircraft engine pressure sensor shell is characterized in that: the method is adopted for repairing the damage.

The conception and the mechanism of the invention are as follows:

firstly, the sleeve material of the pressure sensor shell is martensitic stainless steel 1Cr14Ni3W2VB, the shape of a damaged part is irregular, the depth is inconsistent, in order to ensure the quality of a surfacing layer and recover the service performance of the sleeve, the damaged nitriding layer and oxides need to be cleaned up (the surfacing part comprises a base body and a part of the nitriding layer, and the surfacing environment is complex), and a proper wear-resistant surfacing material is selected. Argon is used as shielding gas, the problems of dilution of a base material and influence of an original nitriding layer on the weld quality in the argon arc welding surfacing process are mainly solved, welding heat input is accurately controlled by selecting proper welding process parameters, and a wear-resistant tissue in alloy is prevented from being dissolved, melted and burnt, so that a surfacing wear-resistant layer with higher quality can be obtained. After welding, the smooth transition of the surface of the welding seam and the good fusion of the base material are required, and the size of the surfacing part is higher than that of the base body of the sleeve.

The invention has the advantages that:

1. compared with the thermal spraying technology, the surfacing welding layer and the base material are metallurgically bonded, so that the bonding strength is high, and the size precision is high; compared with the laser cladding technology, the argon tungsten-arc welding surfacing electric arc has the advantages of being stable in surfacing electric arc, good in accessibility, less in splashing, good in visibility, easy to control the shape of a surfacing layer, good in quality and the like, can guarantee damage repair of irregular shapes and depths, is good in binding force, and is an effective surfacing repair method with strong operability and good repair effect.

2. According to the invention, a manual argon arc welding surfacing technology is adopted, a surfacing material with the brand number of GH40 is selected on a pressure sensor shell sleeve made of martensitic stainless steel 1Cr14Ni3W2VB, excellent surfacing technological parameters are designed, and the problems that the existing sleeve ring replacement repairing process is complicated, the dilution of a base material and the influence of an original nitriding layer on the weld quality and the local repairing of the nitriding layer are difficult to realize in the argon arc welding surfacing process are solved.

3. According to the method, before repair, through a fretting wear test, a wear-resistant material suitable for surfacing and an optimal process parameter for surfacing are selected, so that the problems of complex process and low yield of casing replacement repair of the pressure sensor shell are effectively solved, and the influence of multiple welding on the material structure of the part substrate is avoided. The method completes the repair of the surface damage of the nitriding layer of the martensitic stainless steel material, simultaneously avoids the problems of welding deformation and poor coaxiality caused by sleeve replacement, and has the advantages of good combination of the wear-resistant layer and the matrix after surfacing, no crack and no undercut. The method not only improves the repair quality stability and the use reliability of the pressure sensor shell, greatly reduces the repair cost, but also ensures the normal delivery of the engine, fills the technical blank in the field of repairing the damage fault of the nitriding layer of the sleeve of the pressure sensor shell of the engine, and can be popularized and applied to repairing the damage of the nitriding layer of the martensitic stainless steel part in the fields of aviation, ships and the like.

4. The invention adopts a low-current segmented surfacing (namely, after one-segment welding, argon is introduced by a welding gun to cool a surfacing part, and then a wear-resistant layer is completely surfaced on the damaged part of the sleeve repeatedly in the next segment) during welding, mainly because the surfacing material and the sleeve base material have large plastic difference, the surfacing material is prevented from cracking, the welding stress is reduced, and the good fusion of the surfacing layer and the base and the strength of a bonding surface are ensured.

Drawings

FIG. 1 is a failure diagram of embodiment 1 pressure sensor housing sleeve damage;

FIG. 2 is an overall configuration diagram of a pressure sensor case of embodiment 1;

FIG. 3 is a partial view of a pressure sensor housing sleeve after repair according to example 1;

FIG. 4 is an overall view of the pressure sensor housing repair of embodiment 1;

FIG. 5 is a diagram of the pressure sensor housing after replacement of the housing sleeve;

fig. 6 is a low-magnification photograph of the welding seam part after the casing sleeve is replaced.

Detailed Description

The invention is described in further detail below with reference to the following figures and specific examples:

aiming at the method for repairing the local damage of the nitriding layer on the surface of the casing pipe of the pressure sensor shell of the aircraft engine in the background technology, the overall fault diagram and the structural diagram of the pressure sensor shell are shown in the figures 1 and 2, proper surfacing materials are determined by adopting proper manual argon arc welding surfacing process parameters, welding heat input is strictly controlled, and the repair of the damaged part of the nitriding layer of the casing pipe is realized, and the method comprises the following specific steps:

(1) Determining surfacing material and manual argon arc welding surfacing process parameters

Selecting a surfacing material: selecting GH40 and CoCrW materials with better wear resistance as surfacing materials according to the index that the surface hardness of an original nitriding layer is not less than 80HV, manufacturing a standard ball-disk fretting wear sample, and performing fretting wear by using samples in three states (nitriding layer, surfacing GH40 and surfacing CoCrW)Test, under the same test conditions, the wear volume of the nitriding layer sample is-111641 mu m ³ The abrasion volume of a surfacing GH40 material sample is-15324 mu m ³ The abrasion volume of a surfacing CoCrW material sample is-35123 mu m ³ Compared comprehensively, the wear resistance of the surfacing GH40 material is obviously superior to that of a nitriding layer and a surfacing CoCrW layer, so that the GH40 material is selected as the surfacing material, and the wear resistance of the part repaired by the surfacing material is better than that of the original nitriding layer.

According to the thickness and damage condition (namely depth and shape) of the required surfacing at the damaged part of the sleeve, setting different process parameters for carrying out a welding test until the surfacing part is completely fused and the appearance is flawless (namely the standard of no crack, undercut, air hole and other defects) is met, and determining the process parameters of manual argon arc welding surfacing: welding wire mark: GH40; the specification of the welding wire is as follows:

current intensity: 40A to 45A; the diameter of the tungsten wire is as follows:

inert gas argon is used as shielding gas argon flow: 10L/min to 15L/min; backside argon flow: 4L/min-8L/min; polarity of power supply: the direct current is connected. After overlaying, the external diameter of the overlaying part is required to be not less than

2) Pretreatment before welding

The irregular damage part of the sleeve is polished by a grinding wheel until the metal luster is exposed, the surface to be repaired is kept flat without defects of pits, sharp corners, burrs and the like, and the oil stain and sweat stain on the surface of the polished sleeve are cleaned by alcohol.

3) Build-up welding

3.1 The pressure sensor shell is placed on a welding workbench, the rear end of the pressure sensor shell is padded by a cushion block, and the damaged part of the sleeve is enabled to face upwards so as to facilitate welding.

3.2 Because the difference between the plasticity of the surfacing material and that of the base material of the sleeve is large, in order to prevent cracking of the surfacing layer, reduce welding stress and ensure good fusion of the surfacing layer and the base and the strength of a bonding surface, small-current segmented surfacing is adopted in the surfacing process, namely after one-segment welding is finished, argon is introduced into a welding gun to cool the surfacing part, and then the process is repeated in the next segment of surfacing so as to ensure that the wear-resistant layer is completely surfaced on the damaged part of the sleeve.

4) Postweld treatment (grinding excircle)

And (5) performing finish machining on the surfacing part by using a universal cylindrical grinder, and recovering the outer circle of the sleeve to the original size. In order to ensure the coaxiality of the pressure sensor shell and not damage the original nitriding layer, the grinding amount is 0.1-0.2 mm each time, and the grinding amount is a small amount of grinding for multiple times so as to control the machining deformation and reduce the machining stress. Working until the overlay welding layer is flush with the original nitriding layer, i.e.

The surface roughness Ra is 0.8 μm, the repair is completed, and the qualified pressure sensor shell is repaired as shown in figures 3 and 4, so that the design and use requirements are finally met.

5) Fluoroscopy

And (4) carrying out fluorescence inspection on the surfacing area of the machined part, and finding that the outer surface of the surfacing layer of the sleeve has no crack defect.

6) Effect verification

The following examples were carried out by selecting different process parameters according to the above procedure

Therefore, the method of the invention forms a surfacing part made of composite material on the local part of the sleeve by surfacing a wear-resistant material on the damaged part of the sleeve, the surfacing layer is equivalent to a nitriding layer in use performance, the problems of low welding qualification rate (see figures 5 and 6 and 3 and 5 for the drawing of sleeve replacement and obviously showing better repairing effect of figure 3 than figure 5) and over-poor coaxiality and the like caused by the replacement of the sleeve and the repair of the pressure sensor shell can be avoided, the repair qualification rate of the pressure sensor shell is improved, the repair times and the repair cost are reduced, and the scheme can solve the bottleneck problem of the repair of the pressure sensor shell, and the working stability and the use reliability of an engine are improved.

While the invention has been described with reference to specific embodiments, the invention is not limited thereto, and various equivalent modifications or substitutions can be easily made by those skilled in the art within the technical scope of the present disclosure.

Claims (10)

1. A surfacing repair method for damaged housing of an aircraft engine pressure sensor is characterized by comprising the following steps: the method comprises the following steps:

1) Pre-weld pretreatment

Polishing the damaged part of the casing of the pressure sensor until the metal luster is exposed, keeping the surface to be repaired smooth and free of defects, and cleaning the polished surface of the casing by using alcohol;

2) Build-up welding

Placing the pressure sensor shell pretreated in the step 1) on a welding workbench, ensuring that the damaged part of the sleeve is upward, and performing segmented argon arc welding according to the damaged part by adopting a predetermined surfacing material and a surfacing process to ensure that all the damaged part of the sleeve is surfaced with a wear-resistant layer, wherein the outer diameter of the surfaced part after surfacing is not less than the required size of the pressure sensor shell sleeve;

the segmented welding is that after one-segment welding is finished, argon is introduced into a welding gun to cool a surfacing part, and then the next segment is surfaced;

the surfacing material and the surfacing process are determined by the following method:

s1, selecting at least two surfacing materials with the hardness close to that of the surface of the original nitriding layer of the casing pipe of the pressure sensor and the wear resistance requirement of the casing pipe of the pressure sensor as alternative repairing materials according to the hardness requirement of the surface of the original nitriding layer of the casing pipe of the pressure sensor and the wear resistance requirement of the casing pipe of the pressure sensor;

s2, under the same test condition, comparing the wear volumes of the alternative repairing materials selected in the S1 through a fretting wear test, and determining the surfacing material, wherein the smaller the wear volume is, the better the wear resistance is;

s3, setting different process parameters to perform a welding test according to the thickness and damage condition of the surfacing required by the damaged part of the sleeve until the surfacing part is completely fused and the appearance is free of defects visually, and determining a surfacing process; the determined welding process parameters are as follows:

current intensity: 40A to 45A;

the diameter of the tungsten wire is as follows:

inert gas argon is used as shielding gas argon flow: 10L/min to 15L/min;

back argon flow: 4L/min-8L/min;

polarity of power supply: direct current is connected positively;

3) Post-weld treatment

And (3) performing finish machining on the surfacing part, recovering the excircle of the sleeve to the original size, processing until the surfacing layer is flush with the original nitriding layer, and finishing the damage repair when the surface roughness meets the design requirement of the shell sleeve of the pressure sensor.

2. The aero-engine pressure sensor shell damage bead welding repair method according to claim 1, characterized in that:

in the step 1), the pre-welding pretreatment of the workpiece to be surfacing-welded refers to that the damaged part of the casing of the pressure sensor is polished by using a grinding wheel until the metallic luster is exposed, the surface to be repaired is kept flat and free of pits, sharp corners and burrs, and then oil stains and sweat stains on the surface of the polished casing are cleaned by using alcohol.

3. The aircraft engine pressure sensor shell damage surfacing repair method according to claim 1 or 2, characterized in that:

the pressure sensor shell sleeve is made of martensitic stainless steel 1Cr14Ni3W2VB;

in the step 2), the grade of the selected welding wire is GH40, and the specification is

4. The aircraft engine pressure sensor shell damage surfacing repair method according to claim 3, characterized in that:

and 3) performing finish machining on the surfacing part by using a universal cylindrical grinder, recovering the outer circle of the sleeve to the original size, wherein the finish machining is performed in a small quantity and multiple times, and the grinding quantity is 0.1-0.2 mm each time.

5. The aircraft engine pressure sensor shell damage surfacing repair method according to claim 4, characterized in that:

in step 2), the external diameter of the surfacing part is not less than

6. The aircraft engine pressure sensor shell damage surfacing repair method according to claim 5, characterized in that:

in the step 3), the surface roughness required by the design of the pressure sensor shell sleeve is 0.8 μm.

7. The aircraft engine pressure sensor shell damage surfacing repair method according to claim 6, characterized in that:

in S1, the surface hardness required by the original nitriding layer is not less than 80HV.

8. The aircraft engine pressure sensor shell damage surfacing repair method according to claim 7, characterized in that:

in S3, the specification of the selected welding wire is

The welding process parameters are as follows:

current intensity: 45 an;

diameter of tungsten filament:

inert gas argon was used as shielding gas argon flow: 12L/min;

back argon flow: 6L/min;

polarity of power supply: the direct current is connected.

9. The aero-engine pressure sensor housing damage weld overlay repair method according to claim 1, further comprising step 4):

step 4) fluoroscopy

And performing fluorescence inspection on the surfacing part of the machined part to ensure that the outer surface of the surfacing layer of the sleeve has no crack defect.

10. The utility model provides an aeroengine pressure sensor casing after restoreing which characterized in that: repair of lesions by the method according to any of claims 1 to 9.

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