Femtosecond laser galvanometer scanning machining method for cooling hole of multi-layer-wall turbine blade

Abstract

The invention provides a femtosecond laser galvanometer scanning machining method for a cooling hole of a multi-layer-wall turbine blade. The femtosecond laser galvanometer scanning machining method comprises the following steps of strategy customization, wherein a cooling hole machining strategy is customized; protective filling: carrying out automatic filling to prevent laser from damaging the wall opposite to the hole at the punching moment of the cooling hole; a feature point iterative measurement correction positioning method is adopted, and blade forming errors and clamping errors are compensated; galvanometer scanning is conducted, wherein machining of all cooling holes of the blade is completed at a time; automatic detection: automatically completing the displacement of the blade between femtosecond laser drilling equipment and optical detection equipment; protection removal is conducted, specifically, the blades are automatically in butt joint with a cleaning pump water pipe chuck, and cleaning operation is conducted; hole edge rounding is conducted, specifically, the edge of an inlet and the edge of an outlet of the cooling hole are rounded; and flow checking: forming a water passing state and water flow checking report. And filling and removing of the extremely narrow gap protection material of the inner cavity of the multi-layer-wall turbine blade are facilitated. And the surface quality and the surface regularity of cooling hole machining are greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of turbine blade cooling hole processing technology, in particular to a kind of multilayer wall turbine blade cooling hole femtosecond laser galvanometer scanning processing method. BACKGROUND

[0002] With the development of aero-engine, the comprehensive performance requirements of turbine blade are also improved. In order to improve the service life of blade, the influence of cooling hole geometry, consistency, position and surface quality is greatly reduced, and the advanced turbine blade structure of multilayer wall is proposed to further ensure the reliability of the blade.

[0003] The multilayer wall turbine blade is mostly made of high-temperature alloy material, and the outer wall of the blade body is distributed with multiple rows of cooling holes, which can achieve the effect of film cooling from the structure. In order to make the cooling hole achieve the quality target of no remelt layer, no microcrack and no heat affected zone, at the same time, the problem of easy damage in the process of hole making caused by extremely small wall gap can be solved, and the traditional femtosecond laser rotary cutting processing method cannot meet the processing requirements of multilayer wall turbine blade cooling hole. SUMMARY

[0004] The present application discloses a kind of multilayer wall turbine blade cooling hole femtosecond laser galvanometer scanning processing method, comprising the following steps: strategy customization, protection filling, clamping positioning, galvanometer scanning, automatic detection, protection removal, hole edge rounding and flow check. The present application uses automatic processing method to effectively improve the femtosecond laser multilayer blade body surface superposition wall structure turbine blade cooling hole geometric quantity, processing quality and efficiency, meet the use requirements that cooling hole outlet wall has no laser damage and hole mouth is smooth without sharp edge.

[0005] The problem to be solved by the present application is to change the traditional femtosecond laser rotary cutting hole processing method, and to provide a kind of multilayer wall turbine blade cooling hole femtosecond laser galvanometer scanning processing method for the problem of easy damage of extremely small wall gap.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme: A kind of multilayer wall turbine blade cooling hole femtosecond laser galvanometer scanning processing method, comprising the following steps: S1. Strategy customization: the minimum included angle between cooling hole and adjacent surface of blade, the maximum vector depth, the wall spacing, the hole diameter value and the maximum depth-diameter ratio are counted, and the cooling hole processing strategy is customized; S2. Protection filling: automatic filling is carried out to block the laser from damaging the wall opposite the hole at the moment of punching the hole; S3. Clamping positioning: feature point iterative measurement correction positioning method is used, the position of cooling hole is corrected according to the outermost profile of blade, and the forming error and clamping error of blade are compensated; S4. Galvanometer scanning: according to S1, a galvanometer scanning processing program package for blade cooling hole femtosecond laser is prepared, and all cooling holes of the blade are processed at one time without stopping in the middle; S5. Automatic detection: automatically complete the displacement of the blade between the femtosecond laser hole forming device and the optical detection device, and form the detection and evaluation of the hole diameter, hole angle, hole taper and hole position degree; S6. Protection removal: automatically perform the butt joint of the blade and the cleaning pump water pipe clamp, perform cleaning operation, and remove the excess in the blade inner cavity; S7. Hole edge rounding: adopt automatic mechanical processing method to round the inlet and outlet edges of the cooling hole; S8. Flow check: automatically complete the connection of the blade and the flow machine water pipe clamp, perform water flow check, and form water flow state and water flow check report.

[0007] Preferably, S1 further comprises the following steps: S0. Blade inspection: visually inspect the blade to ensure that there is no scratch, the processing surface and the blade inner cavity should be clean, free of oil stains and excess.

[0008] Preferably, S1 comprises the following steps: S11. Adopt the four-step processing method of pre-punching, punching, removing excess, and inner cavity finishing to perform cooling hole femtosecond laser galvanometer scanning processing; S12. Cylindrical cooling hole adopts concentric circular trajectory arrangement, and the material etching position and etching amount process control are performed through trajectory horizontal and vertical step adjustment.

[0009] S13. Special-shaped cooling hole adopts arch-shaped, back-shaped and parallel line-shaped trajectory arrangement, and the material etching position and etching amount process control are performed through trajectory horizontal and vertical step adjustment.

[0010] Preferably, in step S2, resin type protection material is filled, copper foil is used for sealing, and whether the filling is complete is checked by weighing and perspective.

[0011] Preferably, in step S3, the clamping position relationship is consistent with the processing coordinate system, and the self-adaptive iterative positioning accuracy should be set according to the drawing requirements.

[0012] Preferably, in step S4, coaxial and paraxial two auxiliary blowing modes are used for cooling and slag removal of the processing area.

[0013] Preferably, in step S5, the blade displacement of the processing device and the detection device is completed through the zero point positioning quick change system.

[0014] Preferably, in step S5, the connection between processing and detection is built to reduce displacement error; all cooling holes are scanned at full depth, and the cooling hole processing topography and quality are evaluated by complete topography.

[0015] Preferably, in step S6, whether the blade inner cavity is cleaned is checked by using a small-caliber endoscope.

[0016] Preferably, in step S7, the cooling hole is reciprocally polished by using an oily water-based abrasive.

[0017] Preferably, in step S8, after water is passed, differences such as cooling hole opening, hole angle, string cavity, water column bifurcation and weak water can be distinguished, and each cooling hole needs to be recorded one by one.

[0018] The present application has the following advantages: The present application changes the traditional solid particle protective material and selects a resin material, so that the flowability, adsorbability and easy removal of the protective material in the filling and removal process are improved, and the filling and removal of the protective material in the extremely small gap of the multi-layer wall turbine blade inner cavity are more convenient.

[0019] The present application changes the traditional femtosecond laser rotary cutting scanning mode and adopts a femtosecond laser galvanometer scanning mode, which not only ensures the quality of the cooling hole, but also indirectly improves the processing efficiency by improving the scanning speed; not only can the cylindrical cooling hole be processed, but also the one-time positioning integrated processing of the special-shaped cooling hole can be realized, so that the positioning error problem caused by the two-time positioning processing of the special-shaped part and the cylindrical part in the traditional process is avoided.

[0020] The present application proposes a multi-layer wall turbine blade cooling hole femtosecond laser galvanometer scanning processing method, adopts a four-step integrated processing scheme, solves the problem of splashing damage of adjacent hole surfaces caused by laser processing by pre-punching, adopts a low-power hole forming principle, and completes the hole forming of high surface quality. At the same time, the discharge direction of the recoil splash is constrained, and the surface quality is greatly improved; the through hole solves the problem of single recoil chip removal mode in the laser hole forming process, and the smooth chip removal channel provides a more reliable process control environment for the subsequent excess amount removal and inner cavity finishing; the excess amount removal solves the problem of non-standard roundness and taper of the cooling hole; the inner cavity finishing solves the problem of residual burr and remelt layer of the inner wall of the cooling hole, greatly improves the surface quality and surface regularity of the cooling hole processing.

[0021] The present application proposes automation processing requirements in protective filling, clamping positioning, galvanometer scanning, automatic detection, protective removal and flow check, and meets the needs of aviation manufacturing enterprises gradually transforming to automation and digitization. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application.

[0023] Figure 1This is a schematic diagram of the femtosecond laser galvanometer scanning method for processing cooling holes in multi-walled turbine blades. 1. Focusing lens; 2. Plasma; 3. Outer wall of substrate; 4. Resin-based protective material; 5. Inner wall of substrate. Figure 2 This is a schematic diagram illustrating the femtosecond laser galvanometer scanning process for processing cooling holes in multi-walled turbine blades. 6. Laser, 7. Beam expander, 8. Waveplate, 9. X-axis motor, 10. X-axis rotating rod, 11. X-axis galvanometer, 12. Y-axis motor, 13. Y-axis rotating rod, 14. Y-axis galvanometer, 15. Focusing lens, 16. Worktable, 17. Fixture base, 18. Chuck, 19. Spherical positioning post, 20. Blade; Figure 3 This is a schematic diagram of a four-step process for femtosecond laser galvanometer scanning machining of cylindrical cooling holes in multi-walled turbine blades. Figure 4 This is a schematic diagram of the concentric circle trajectory of femtosecond laser galvanometer scanning machining of cylindrical cooling holes in multi-walled turbine blades; Figure 5 This is a schematic diagram of the bow-shaped trajectory processed by femtosecond laser galvanometer scanning of irregular cooling holes in multi-walled turbine blades; Figure 6 This is a schematic diagram of the U-shaped trajectory of femtosecond laser galvanometer scanning processing of irregular cooling holes in multi-walled turbine blades; Figure 7 This is a schematic diagram of the parallel linear trajectory of the femtosecond laser galvanometer scanning process for the irregular cooling holes of a multi-walled turbine blade. Figure 8 This is a topographic image of the cooling hole morphology processed by femtosecond laser galvanometer scanning on a multi-walled turbine blade. Detailed Implementation

[0024] The processing methods in the embodiments of the present invention will be described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, and not all embodiments.

[0025] Unless otherwise specifically stated, the relative arrangement, mathematical expressions, and numerical values ​​of the components and steps described in these embodiments do not limit the scope of this application.

[0026] Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification.

[0027] In all the examples shown herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0028] This embodiment provides a femtosecond laser galvanometer scanning method for processing cooling holes in multi-walled turbine blades. The processing method and principle are as follows: Figure 1and attached Figure 2 As shown, it includes the following steps: Statistically analyze the minimum included angle, maximum vector depth, wall spacing, hole diameter, and maximum depth-to-diameter ratio between the cooling hole and the adjacent surface of the blade, and customize the cooling hole processing strategy.

[0029] S11. As attached Figure 3 As shown, a four-step processing method is adopted, namely pre-drilling, through-hole drilling, excess material removal, and internal cavity finishing, for the femtosecond laser galvanometer scanning processing of the cooling hole; S12. As attached Figure 4 As shown, the cylindrical cooling holes are arranged in a concentric circular trajectory, and the material removal location and amount are controlled by adjusting the horizontal and vertical steps of the trajectory.

[0030] S13. As attached Figure 5 Appendix Figure 6 and attached Figure 7 The irregularly shaped cooling holes shown are arranged in a bow-shaped, square-shaped, or parallel line trajectory. The material removal location and amount are controlled by adjusting the horizontal and vertical steps of the trajectory.

[0031] Preferably, in step S11, the pre-drilling depth is only 10% to 20% of the hole depth, the through-hole and allowance removal depth is the remaining part after deducting the pre-drilling depth, and the inner cavity finishing depth is the full vector depth. The processing strategy is as follows: pre-drilling completes rough processing in one go, with a power of only 20%; through-hole drilling is completed and then the light is turned off, with a power of 80%; allowance removal starts from 1 / 2 of the vector depth, with a power of 60%; finishing is the entire inner cavity surface processing, with a power of 20%.

[0032] Preferredly, in step S2, a resin-based protective material is used for filling, and copper foil is used for sealing. The filling is checked for completeness by iterative filling under vacuum, weighing, or optical imaging. Automatic filling is performed to prevent the laser from damaging the opposite wall of the cooling hole at the moment of penetration. During the process, the resin-based protective material is injected into the blade to be processed, which can be done using a syringe injection method. The leakage of solution from the other end outlet is observed. If necessary, the filled blade should be placed in a vacuum degassing chamber for vacuuming, then removed and re-injected with resin. This process is repeated multiple times to ensure that air is removed from the blade. To prevent premature resin curing, the filling process should be completed within 0.5-1 hour. After complete filling, the blade should be allowed to cure naturally for 4-8 hours, or at a temperature of 60℃-80℃ for 1-1.5 hours. Processing can proceed after complete curing.

[0033] Prioritize that, in step S3, the clamping position relationship is consistent with the machining coordinate system, and the adaptive iterative positioning accuracy should be set according to the drawing requirements. During the process, the fit between the spherical positioning post and the blade tenon end face needs to be checked; a 0.03mm feeler gauge failure is considered acceptable. A feature point iterative measurement correction positioning method is used to readjust the cooling hole positions based on the outermost contour surface of the blade, compensating for blade forming errors and clamping errors. During the point sampling process, ensure the sensor is perpendicular to the point to be sampled to avoid interference. Record all measurements after completion. Perform adaptive positioning on the blade, repeating 15-20 times, and take the minimum value as the positioning result. Perform hole position compensation on all cooling holes on the blade, measuring along the normal direction. Accurately retrieve the original hole position data before hole position compensation.

[0034] Prioritize the development of a femtosecond laser galvanometer scanning machining program for the blade cooling holes based on step S1, completing the machining of all cooling holes in one go without interruption. In step S4, both coaxial and off-axis auxiliary air blowing modes are used simultaneously for cooling and slag removal in the machining area. The coaxial and off-axis air pressures are both ≥0.6MPa, and the scanning speed is ≥5m / s.

[0035] Prioritized, in step S5, the displacement of the blade between the femtosecond laser drilling equipment and the optical inspection equipment is automatically completed by the zero-point positioning quick-change system, resulting in the detection and evaluation of hole diameter, hole angle, hole taper, and hole position. The repeatability of the displacement process is ≤0.01mm.

[0036] Prioritizes establishing a connection between machining positioning accuracy and detection positioning accuracy in step S5 to reduce displacement errors; performs a full-depth scan of all cooling holes and evaluates the machining quality of the cooling holes using their actual morphology. The error between the scanned image and the actual part is ≤0.01mm.

[0037] Prioritizes step S6 by using a small-diameter endoscope to check if the inner cavity of the blade is clean. The blade and cleaning pump water pipe are automatically repositioned for cleaning to remove excess material from the inner cavity of the blade. Each cleaning cycle lasts 3 minutes, with a 1-minute interval between cycles, and the number of cycles is ≤3. After cleaning, the blade is placed in a drying oven at 100±5℃ for 4 hours, and then stored in a moisture-proof box.

[0038] Preferredly, in step S7, the cooling holes are reciprocatedly polished using an oil-based water-based abrasive. An automated machining method is then used to round the inlet and outlet edges of the cooling holes. After machining, the radius of the corner radius of the cooling hole should be between R0.05mm and R0.1mm to completely eliminate stress concentration caused by sharp edges at the hole opening. The morphology of the cooled hole after machining is as follows: Figure 8 As shown.

[0039] Prioritized, in step S8, after water flow, differences in cooling hole continuity, hole angle, cross-cavity flow, water column bifurcation, and water weakness can be identified and recorded one by one according to the cooling hole number. The system automatically connects the blades to the flow meter water pipe, performs water flow checks, and generates a water flow status and inspection report. Different sealing sheet structures are used for water flow checks to achieve both chamber-specific and overall chamber flow checks, with a water pressure of 0.2MPa-0.3MPa.

[0040] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0041] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0042] Matters not covered in this invention are common knowledge.

[0043] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for femtosecond laser galvanometer scanning to process cooling holes in multi-walled turbine blades, characterized in that, Includes the following steps: S1. Strategy Customization: Statistically analyze the minimum included angle, maximum vector depth, wall spacing, hole diameter, and maximum depth-to-diameter ratio between the cooling hole and the adjacent surface of the blade to customize the cooling hole processing strategy; S2. Protective filling: Automatic filling is performed to prevent the laser from damaging the opposite wall of the cooling hole at the moment it penetrates the cooling hole; S3. Clamping and positioning: The feature point iterative measurement and correction positioning method is adopted to re-correct the position of the cooling hole according to the outermost contour surface of the blade, and to compensate for the blade forming error and clamping error. S4. Galvanometer Scanning: Based on S1, a femtosecond laser galvanometer scanning machining program package for blade cooling holes is developed to complete the machining of all cooling holes on the blade in one go without interruption. S5. Automatic detection: Automatically completes the displacement of the blade between the femtosecond laser drilling equipment and the optical detection equipment, forming the detection and evaluation of hole diameter, hole angle, hole taper and hole position; S6. Protective Removal: Automatically connects the blades to the cleaning pump water pipe clamp to perform a cleaning operation and remove excess material from the inner cavity of the blades; S7. Hole edge rounding: The edges of the cooling hole inlet and outlet are rounded using automated machining methods; S8. Flow Check: Automatically connects the blades to the water pipe clamp of the flow meter, checks the water flow, and generates a water flow status and water flow check report.

2. The femtosecond laser galvanometer scanning method for processing cooling holes in multi-walled turbine blades according to claim 1, characterized in that, Before S1, the following steps are also included: S0. Blade inspection: Visual inspection of the blades shall not allow any scratches or dents, and the machined surfaces and inner cavities of the blades shall be clean, free of oil stains and foreign matter.

3. The femtosecond laser galvanometer scanning method for processing cooling holes in multi-walled turbine blades according to claim 1, characterized in that, S1 includes the following steps: S11. The cooling hole is processed by femtosecond laser galvanometer scanning using a four-step processing method: pre-drilling, through-hole drilling, excess material removal, and internal cavity finishing. S12. The cylindrical cooling holes are arranged in a concentric circular trajectory, and the material removal location and amount are controlled by adjusting the horizontal and vertical steps of the trajectory. S13. Irregularly shaped cooling holes are arranged in a bow-shaped, square-shaped, or parallel line trajectory. The material removal location and amount are controlled by adjusting the horizontal and vertical steps of the trajectory.

4. The femtosecond laser galvanometer scanning method for processing cooling holes in multi-walled turbine blades according to claim 1, characterized in that, Resin-based protective materials are used for filling, and copper foil is used for sealing. The filling is checked by vacuuming and iterative filling, weighing, or using X-ray inspection to ensure complete filling.

5. The femtosecond laser galvanometer scanning method for processing cooling holes in multi-walled turbine blades according to claim 1, characterized in that, The clamping position relationship should be consistent with the machining coordinate system, and the adaptive iterative positioning accuracy should be set according to the drawing requirements.

6. The femtosecond laser galvanometer scanning method for processing cooling holes in multi-walled turbine blades according to claim 1, characterized in that, Simultaneously, both coaxial and off-axis auxiliary air blowing modes are used for cooling and slag removal in the processing area.

7. The femtosecond laser galvanometer scanning method for processing cooling holes in multi-walled turbine blades according to claim 1, characterized in that, The blades of the processing equipment and the testing equipment are moved using a zero-point positioning quick-change system.

8. The femtosecond laser galvanometer scanning method for processing cooling holes in multi-walled turbine blades according to claim 7, characterized in that, Establish a connection between processing and inspection to reduce displacement errors; perform full-depth scanning of all cooling holes and use complete morphology to evaluate the processing morphology and quality of the cooling holes.

9. The femtosecond laser galvanometer scanning method for processing cooling holes in multi-walled turbine blades according to claim 1, characterized in that, Use a small-diameter endoscope to check if the inner cavity of the blade is clean; use oil-based water-based abrasives for reciprocating polishing.

10. The femtosecond laser galvanometer scanning method for processing cooling holes in multi-walled turbine blades according to claim 1, characterized in that, After water is introduced, the following characteristics are identified: the opening of the cooling holes, the hole angle, the cross-cavity, the water column bifurcation, and the water flow differences. These are then recorded one by one according to the cooling hole number.

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