CN112621103B - Repair method for titanium alloy blade of aircraft engine compressor - Google Patents

Abstract

The invention relates to a repairing method for a titanium alloy blade of an aero-engine compressor, which includes pre-welding cleaning of the titanium alloy compressor blade, processing and grinding of the parts to be welded, non-destructive testing before welding, microbeam plasma arc welding, post-weld heat treatment, and post-weld heat treatment. Electrolytic machining and non-destructive testing. The invention can be used for welding repair of engine compressor blades, fills the technical blank of domestic engine key components welding repair, reduces the maintenance cost of key components and shortens the maintenance period.

Description

Repair method of titanium alloy blade of aero-engine compressor

technical field

The invention belongs to the technical field of welding, and in particular relates to a repairing method for a titanium alloy blade of an aero-engine compressor.

Background technique

As one of the key components of aero-engine, the compressor blade is located at the intake end of the engine. During the service process, the blade size is missing due to foreign object impact, airflow scouring, friction and wear and other reasons. Welding, repairing and processing damaged compressor blades to restore the outer dimensions of the blades can reduce the number of new blades to be replaced, shorten the maintenance period, and reduce the cost of the entire life of the engine.

Due to residual sealing rings, gaskets, lubricants, etc. on the surface of the compressor blade after service, and there is an oxide film on the surface, if it is not thoroughly cleaned, the welding quality will be affected. Due to the huge alternating stress in the service process of the engine blade, high requirements are placed on the surface integrity of the repaired blade. The traditional method of surface vibration finishing and shot peening after machining is more expensive and costly. higher.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art, and to provide a method for repairing titanium alloy blades of aero-engine compressors. Complex motion trajectory; precise forming and repairing of compressor blades can be achieved. There are no cracks and inclusions in the welding repair area, and the welding seam is fully formed, and a certain machining allowance is reserved.

The present invention solves its technical problem and realizes through the following technical solutions:

A method for repairing titanium alloy blades of aero-engine compressors, characterized in that: the repairing method comprises the following steps:

Step 1: Clean the titanium alloy compressor blades before welding;

Step 2: Process the parts to be welded on the titanium alloy compressor blade;

Step 3: Nondestructive testing of titanium alloy compressor blades;

Step 4: Microbeam plasma arc welding of titanium alloy compressor blades;

Step 5: post-weld heat treatment of titanium alloy compressor blades;

Step 6: Electrolytic machining is performed on the welding area of the titanium alloy compressor blade;

Step 7: Perform non-destructive testing on the welded repaired blades of the titanium alloy compressor.

Moreover, the specific operation of cleaning before welding in the step 1 is as follows: using acetone organic solvent to preliminarily clean the blade, and thoroughly cleaning the remaining sealing ring, gasket and lubricant on the blade; for the oxide film on the blade surface, through Pickling is used for cleaning. The pickling temperature is 30-60°C, the pickling time is 1-10min, and the pickling corrosion amount is 0.02mm. The formula of the pickling solution used for the pickling is:

Nitric acid 10-20%

Hydrofluoric acid 50-60%

Distilled water 20-40%.

Moreover, in the compressor blade of step 2, after the damaged part is cut with a water jet, the cut surface is ground from coarse to fine until the roughness is better than Ra0.1-0.05.

Moreover, in the compressor blade of step 3, the blade is inspected for cracks according to the fluorescent liquid penetration inspection standard.

In addition, the compressor blade in step 4 is clamped by a flexible clamping mechanism, and the surface of the damaged blade to be welded is required to be 0.5-3.0 mm higher than the clamp; according to the missing size of the blade profile and the surfacing height of each weld, determine The number of weld bead repaired by surfacing; set the welding track as the center line of the surface to be welded, the arc starting position is 0.5-3.0 mm in front of the leading edge of the blade to be welded, and the arc ending position is 0.5-3.0 mm behind the trailing edge of the blade to be welded mm, the height of the starting/finishing arc position is 2.0-5.0mm above the surface of the blade to be welded; the welding uses high-purity argon gas to build a triple protective atmosphere, the flow rate of the molten pool shielding gas is 20-40SCFH, the outlet is located directly above the molten pool, vertically downward Blow to the molten pool, the protective gas flow on the front of the weld is 100~200SCFH, the outlet is located directly above the weld, blow vertically downward to the weld, the protective gas flow on the back of the weld is 3~10SCFH, the outlet is located on the blade clamping tool, Blow laterally to the root of the weld; the welding process is as follows:

(1) Move the welding torch to the arc starting position, turn on the protective gas of the molten pool, the protective gas on the front of the welding seam, and the protective gas on the back of the welding seam, stay for 20-50 seconds, and remove the air in the welding area to avoid oxygen, nitrogen and hydrogen in the air. Elements enter the molten pool and deteriorate the performance of the welded joint;

(2) Stay at the arc starting position for 1-10s after starting the arc. After the plasma arc is stabilized, the welding current is maintained at a low power. The surfacing welding is carried out with lower power and larger wire feeding amount, so that the leading edge of the surfacing area of the blade is full and sufficient machining allowance is left;

(3) The welding torch continues surfacing at the welding heat input and wire feeding speed suitable for the width of the weld;

(4) Start to reduce the welding current and increase the wire feeding rate at the position 2-10mm away from the trailing edge of the blade, and the welding gun moves to the arc-end position of the blade under the guidance of the manipulator to avoid the collapse of the trailing edge;

(5) The plasma arc is closed at the arc end position, and the welding wire is withdrawn from the molten pool at the same time. After the temperature of the surfacing area is cooled to less than 200 °C, the shielding gas is turned off, and the first weld surfacing is completed;

(6) Repeat the above welding process until the designed number of weld beads is reached.

Moreover, the compressor blade in the step 5 is subjected to stress relief heat treatment in a vacuum or argon atmosphere, and the heat treatment temperature is not higher than the phase transition temperature of the titanium alloy.

Moreover, in the compressor blade of the step 6, the excess titanium alloy in the surfacing area is removed by electrolytic machining, the cathode of the electrolytic machining adopts the dispersing hole water outlet method, and the electrolyte adopts NaCl as the basis of the electrolyte, and adds a complexing agent; The electrolysis voltage is 20V, the current density is 55-65A/cm ² , the processing gap is 0.2-1.8cm, and the processing speed is 0.15-0.20mm/s.

Moreover, in the compressor blade of step 7, visual inspection, X-ray inspection and fluorescent penetration inspection are used for appearance, and the relevant dimensions of the blade are inspected at the same time to confirm that the damaged repair area is complete and clean, and there is no undercut or hole defect, and the repair area is complete. The front and rear edges are full in shape without collapse, and the appearance color is silvery white or light golden yellow.

The advantages and beneficial effects of the present invention are:

The method for repairing titanium alloy blades of aero-engine compressors in the present invention adopts a multi-axis linkage robot to drive a welding torch to realize a complex motion trajectory in three-dimensional space, optimizes process parameters by synthesizing the welding process of the front and rear edges and the welding of titanium alloy plates, and sets each segment of the blade in sections. The welding process parameters of the upper edge and the fitting trajectory planned according to the automatic welding system can weld a compressor blade with a full shape of the weld and no collapse of the front and rear edges, which ensures the quality and accuracy of the blade repair.

Description of drawings

Fig. 1 is the structural representation of the damaged blade of the aero-engine compressor of the present invention;

Fig. 2 is the titanium alloy effect figure after the pickling of the present invention; (a) is the front cleaning effect figure, (b) is the side cleaning effect;

Fig. 3 is a schematic diagram of cutting and machining titanium alloy blade of aero-engine compressor of the present invention;

Fig. 4 is a schematic diagram of welding trajectory planning of titanium alloy blade of aero-engine compressor of the present invention;

5 is a schematic structural diagram of a compressor blade after surfacing welding of the present invention;

FIG. 6 is a schematic diagram of the structure of the compressor blade after electrolytic machining.

Detailed ways

The present invention will be further described in detail below through specific examples. The following examples are only descriptive, not restrictive, and cannot limit the protection scope of the present invention.

A method for repairing a titanium alloy blade of an aero-engine compressor, the innovation of which is that the repair method comprises the following steps:

Step 1. Cleaning of blades before welding: For the damaged compressor blades as shown in Figure 1, firstly use organic solvents such as acetone to preliminarily clean the blades, and thoroughly clean the remaining sealing rings, gaskets, lubricants, etc. on the blades Cleaning: For the oxide film on the surface of the blade, it is cleaned by pickling. The formula of the pickling solution is as follows: nitric acid (10-20%), hydrofluoric acid (50-60%) and distilled water (the balance), and the pickling temperature is 30- 60 ℃, pickling time 1-10 minutes, the titanium alloy surface cleaned by this process has no oxide film residue, and the pickling corrosion amount is 0.02mm; the cleaned titanium alloy sample is shown in Figure 2.

Step 2. Processing of the part to be welded: As shown in Figure 3, after cutting the damaged part with a water jet, grind the cut surface from coarse to fine until the roughness is better than Ra0.1-0.05.

Step 3. Non-destructive testing before welding: Check the blade for cracks according to the fluorescent liquid penetration inspection standard. If any cracks that have not been removed by processing are found, repeat from Step 1.

Step 4. Micro-beam plasma arc welding: use a flexible clamping mechanism to clamp, and the surface of the damaged blade to be welded is required to be 0.5-3.0 mm higher than the clamp; according to the missing size of the blade profile and the surfacing height of each weld, determine the surfacing welding The number of repaired weld beads; as shown in Figure 4, the vision system is used to extract the contour of the blade surface to be welded through grayscale changes, the welding track is set as the centerline of the to-be-welded surface, and the arc starting position is set as the leading edge of the blade's to-be-welded surface 0.5-3.0mm in front, the arc ending position is 0.5-3.0mm behind the trailing edge of the blade surface to be welded, and the height of the starting/finishing arc position is 2.0-5.0mm above the blade surface to be welded; the welding process uses high-purity argon to build a triple protective atmosphere , the outlet of molten pool protective gas (flow rate is 20-40SCFH) is located directly above the molten pool, blowing vertically downward to the molten pool, and the outlet of the protective gas (100-200SCFH) on the front of the weld is located directly above the weld, blowing vertically downward The welding seam, the protective gas (3~10SCFH) outlet on the back of the welding seam is located on the blade clamping tool, and blows laterally to the root of the welding seam; the welding process is as follows:

(1) Move the welding torch to the arc starting position, turn on the protective gas of the molten pool, the protective gas on the front of the welding seam, and the protective gas on the back of the welding seam, stay for 20-50 seconds, and remove the air in the welding area to avoid oxygen, nitrogen and hydrogen in the air. and other elements enter the molten pool and deteriorate the performance of the welded joint;

(2) Stay at the arc starting position for 1-10s after starting the arc. After the plasma arc is stabilized, the welding current is maintained at a low power. The surfacing welding is carried out with lower power and larger wire feeding amount, so that the leading edge of the surfacing area of the blade is full and sufficient machining allowance is left;

(3) The welding torch continues surfacing at the welding heat input and wire feeding speed suitable for the width of the weld;

(4) Start to reduce the welding current and increase the wire feeding rate at the position 2-10mm away from the trailing edge of the blade, and the welding gun moves to the arc-end position of the blade under the guidance of the manipulator to avoid the collapse of the trailing edge;

(5) Close the plasma arc at the arc end position, and at the same time, the welding wire is withdrawn from the molten pool. After the temperature of the surfacing area is cooled to less than 200 °C, the shielding gas is turned off to complete the first weld surfacing. If the number of welds is greater than one, the welding process can be repeated until the designed number of welds is reached. The compressor blade after surfacing is shown in Figure 5.

Step 5. Post-weld heat treatment: perform stress relief heat treatment in a vacuum or argon atmosphere, and the heat treatment temperature is not higher than the phase transition temperature of the titanium alloy.

Step 6. Electrolytic machining after welding: remove the excess titanium alloy in the surfacing area by electrolytic machining. The cathode of electrolytic machining adopts the solution of dispersing and emptying water, and the electrolyte adopts NaCl as the basis of the electrolyte, and adds a complexing agent; the electrolytic voltage is 20V , the current density is 55～65A/cm ² , the processing gap is 0.2～1.8cm, and the processing speed is 0.15～0.20mm/s. The compressor blade after electrolytic machining is shown in Figure 6.

Step 7. Post-weld non-destructive inspection: use visual inspection, X-ray inspection and fluorescence penetration inspection, and at the same time, inspect the relative dimensions of the blade to confirm that the damaged repair area is complete, clean, free from defects such as undercuts and holes, and the front and rear edges of the repair area are repaired. The shape is full, without collapse, and the appearance color is silvery white or light golden yellow.

Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the invention and the appended claims Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims (7)

1. A method for repairing a titanium alloy blade of an aircraft engine compressor is characterized by comprising the following steps: the repairing method comprises the following steps:

step 1: cleaning the titanium alloy compressor blade before welding;

and 2, step: processing a part to be welded of a titanium alloy compressor blade;

and step 3: carrying out nondestructive testing on the titanium alloy compressor blade;

and 4, step 4: carrying out micro-plasma arc welding on the titanium alloy compressor blade; the blades of the gas compressor are clamped by a flexible clamping mechanism, and the surface to be welded of the damaged blade is required to be 0.5-3.0 mm higher than a chuck; determining the number of weld passes for surfacing repair according to the missing size of the profile of the blade and the surfacing height of each weld joint; setting a welding track as a central line of the surface to be welded, wherein an arc starting position is 0.5-3.0 mm in front of a front edge of the surface to be welded of the blade, an arc receiving position is 0.5-3.0 mm behind a rear edge of the surface to be welded of the blade, and the height of the arc starting/receiving position is 2.0-5.0mm above the surface to be welded of the blade; the welding adopts high-purity argon to construct triple protective atmosphere, the flow of protective gas of a molten pool is 20-40SCFH, an outlet is positioned right above the molten pool and blows towards the molten pool vertically and downwards, the flow of protective gas on the front side of a welding seam is 100-200 SCFH, the outlet is positioned right above the welding seam and blows towards the welding seam vertically and downwards, the flow of protective gas on the back side of the welding seam is 3-10 SCFH, and the outlet is positioned on a blade clamping tool and blows towards the root part of the welding seam laterally; the welding process is as follows:

(1) moving a welding gun to an arc striking position, starting molten pool shielding gas, welding seam front shielding gas and welding seam back shielding gas, staying for 20-50 seconds, and removing air in a welding area to avoid oxygen, nitrogen and hydrogen elements in the air from entering a molten pool to deteriorate the performance of a welding joint;

(2) keeping for 1-10 s after arcing at an arcing position, keeping the welding current at a lower power after plasma arc is stabilized, moving a welding gun to be 2.0-5.0mm right above the front edge of the surface to be welded of the blade under the guidance of a manipulator, and carrying out surfacing welding at a lower power and a larger wire feeding amount to enable the front edge of a surfacing area of the blade to be full and leave enough machining allowance;

(3) the welding gun continues surfacing at a welding heat input amount and a wire feeding speed which are suitable for the width of the welding seam;

(4) starting to reduce welding current at a position 2-10mm away from the rear edge of the blade, improving the wire feeding speed, and moving a welding gun to the arc closing position of the blade under the guidance of a manipulator to avoid the collapse of the rear edge;

(5) closing plasma arcs at arc withdrawing positions, simultaneously drawing back welding wires to be separated from a molten pool, closing protective gas after the temperature of a surfacing area is cooled to be lower than 200 ℃, and finishing first-pass weld surfacing;

(6) repeating the welding process until the number of the welding passes reaches the designed number;

and 5: carrying out postweld heat treatment on the titanium alloy compressor blade;

and 6: carrying out electrolytic machining on a blade welding area of the titanium alloy compressor;

and 7: and carrying out nondestructive testing on the welding repair blade of the titanium alloy compressor.

2. The method for repairing the titanium alloy blade of the aircraft engine compressor as claimed in claim 1, wherein the specific operations of cleaning before welding in the step 1 are as follows: primarily cleaning the blade by using an acetone organic solvent, and thoroughly cleaning a sealing ring, a sealing gasket and a lubricant which are remained on the blade; cleaning an oxide film on the surface of a blade by pickling, wherein the pickling temperature is 30-60 ℃, the pickling time is 1-10 min, the pickling corrosion amount is 0.02mm, and the formula of pickling solution used for pickling is as follows:

10 to 20 percent of nitric acid

50 to 60 percent of hydrofluoric acid

20-40% of distilled water.

3. The method for repairing the titanium alloy blade of the aircraft engine compressor as claimed in claim 1, wherein the compressor blade in the step 2 is cut at the damaged part by a water jet cutter, and then the cut surface is polished from coarse to fine until the roughness is better than Ra0.1-0.05.

4. The method for repairing the titanium alloy blade of the aircraft engine compressor as claimed in claim 1, wherein the crack of the compressor blade in the step 3 is inspected according to a fluorescent liquid penetration inspection standard.

5. The method for repairing the titanium alloy blade of the aircraft engine compressor as claimed in claim 1, wherein: and (5) performing stress relief heat treatment on the compressor blade in the step 5 in a vacuum or argon atmosphere environment, wherein the heat treatment temperature is not higher than the phase transition temperature of the titanium alloy.

6. The method for repairing the titanium alloy blade of the aircraft engine compressor as claimed in claim 1, wherein: removing redundant titanium alloy in the surfacing area of the compressor blade in the step 6 through electrolytic machining, wherein the cathode of the electrolytic machining adopts a dispersed hole water outlet mode, and the electrolyte adopts NaCl as the basis of the electrolyte and is added with a complexing agent; the electrolytic voltage is 20V, and the current density is 55-65A/cm ² The machining gap is 0.2-1.8 cm, and the machining speed is 0.15-0.20 mm/s.

7. The method for repairing the titanium alloy blade of the aircraft engine compressor as claimed in claim 1, wherein: and 7, detecting the relevant sizes of the compressor blades by adopting visual appearance detection, X transmission detection and fluorescence penetration detection, and confirming that the damaged repairing area is complete and clean without undercut and hole defects, the front edge and the rear edge of the repairing area are full in appearance and have no collapse, and the appearance color is silvery white or light golden yellow.

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