Method for generating and protecting the protective device for air film holes in hollow blades

Abstract

This invention relates to the field of aero-engine technology, and discloses a method for generating a protective device and a protective method for machining film cooling holes on hollow blades. The aim is to prevent laser damage to the inner cavity of hollow aero-engine blades during film cooling hole machining. The main methods include: determining a three-dimensional model of the hollow blade to be machined; marking the inner cavity wall surfaces requiring protection in the three-dimensional model of the blade according to the location of the film cooling holes; generating a corresponding three-dimensional model of the protective device based on the marked inner cavity wall surfaces, and generating the corresponding protective device based on the three-dimensional model of the protective device; before using laser to machine the film cooling holes, inserting the protective device into the inner cavity through the cooling airflow inlet of the hollow blade and fixing it in place. This invention avoids laser damage to the wall surface, improves the machining quality of the small hole outlet, and also improves the yield, quality, and lifespan of high-pressure turbine blades, making it particularly suitable for aero-engines.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, specifically to a method for generating and protecting a protective device for machining film holes in hollow blades. Background Technology

[0002] During aero-engine operation, high-pressure turbine guide vanes, as one of the hot-end components, are subjected to the impact of high-temperature and high-pressure combustion gases. Given the limited high-temperature resistance of alloy materials, high-pressure turbine guide vane cooling technology has become an effective way to improve turbine inlet temperature and ensure the turbine's normal and reliable operation in high-temperature service environments. Film cooling holes allow high-pressure turbine guide vanes made of the same material to operate normally in higher-temperature environments. The film cooling holes in hollow blades have a significant impact on engine performance, effectively improving the machining capability and efficiency of blade film cooling holes, and have become an important research area in the aero-engine field. Femtosecond laser processing technology, with its high machining accuracy, absence of a heat-affected zone, and lack of material selection, has become a new generation of cutting-edge key technology for machining film cooling holes in hollow blades. However, when using femtosecond lasers to process blades such as high-pressure turbine guide vanes, the close proximity of the inner cavities of the blades leads to wall damage during machining. This inevitably affects the quality and lifespan of the hollow high-pressure turbine blades, significantly reducing the yield of high-pressure turbine blades.

[0003] Application publication number CN106583949A discloses an online automatic judgment method for monitoring film film hole penetration in blades, achieving wall protection during the processing. Specifically, it uses online third-party software for "penetration monitoring" and "penetration monitoring coordinates" to continuously monitor and automatically interpret the drilling process, thereby achieving online automatic judgment for film film hole penetration monitoring in single-crystal high-pressure vortex hollow blades of aero-engines. For high-pressure turbine guide vane repair parts, when using the "penetration monitoring" method, due to the uneven thickness along the penetration direction and the numerous small holes on the blade, it is difficult to guarantee the exit morphology and size. According to experimental verification, when the wall distance is less than approximately 10 mm, laser damage may still occur at the wall position within the inner cavity. Summary of the Invention

[0004] This invention aims to solve the problem of laser damage to the inner cavity of hollow blades during the processing of air film holes in existing technologies, and proposes a method for generating a protective device and a protective method for processing air film holes in hollow blades.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] In a first aspect, a method for generating a protective device for machining air film holes in hollow blades is provided, the method comprising:

[0007] Determine the 3D model of the hollow blade to be processed;

[0008] According to the location of the air film hole to be processed, mark the inner cavity wall surface that needs to be protected in the three-dimensional model of the blade. The marked inner cavity wall surface includes at least the inner cavity reinforcing rib structure, the supporting protrusion structure and the blade cross section exit shape.

[0009] A three-dimensional model of the corresponding protective device is generated based on the marked inner cavity wall surface, and a corresponding protective device is generated based on the three-dimensional model of the protective device.

[0010] Furthermore, a corresponding 3D model of the protective device is generated based on the marked inner cavity wall surface, specifically including:

[0011] Measure the normal thickness of each internal cavity reinforcing rib structure and each supporting protrusion structure, and determine the maximum normal thickness. After completion, delete the internal cavity reinforcing rib structure and supporting protrusion structure in the blade 3D model, and only retain the basic geometric model of the internal cavity.

[0012] In the basic geometric model, the edge contour curves of the two end faces of the inner cavity are extracted respectively, and the edge contour curves of the two end faces are offset inward in a normal direction. The offset distance is determined according to the maximum normal thickness.

[0013] The edge contour curves after the two end faces of the inner cavity are offset are used as the boundary curves of the protective device, and a complete three-dimensional model of the protective device is established based on the boundary curves.

[0014] Furthermore, the offset distance is the sum of the maximum normal thickness and the preset thickness, where the preset thickness is 0.3 to 0.8 mm.

[0015] Furthermore, the method for generating a corresponding protective device based on the three-dimensional model of the protective device includes:

[0016] The protective device is manufactured based on a three-dimensional model of the protective device and using a molding method, wherein the molding method is casting, 3D printing or machining.

[0017] Furthermore, the protective device is made of a material resistant to laser damage, which includes one or more of the following: steel, aluminum alloy, titanium alloy, high-temperature alloy, ceramic, graphite, and paraffin wax.

[0018] Secondly, a method for protecting the film cooling holes during machining on hollow blades of an aero-engine is provided, the method comprising:

[0019] Determine the 3D model of the hollow blade to be processed;

[0020] According to the location of the air film hole to be processed, mark the inner cavity wall surface that needs to be protected in the three-dimensional model of the blade. The marked inner cavity wall surface includes at least the inner cavity reinforcing rib structure, the supporting protrusion structure and the blade cross section exit shape.

[0021] Generate a corresponding 3D model of the protective device based on the marked inner cavity wall surface, and generate the corresponding protective device based on the 3D model of the protective device.

[0022] Before using laser processing for air film holes, the protective device is inserted into the inner cavity through the cooling airflow inlet of the hollow blade and fixed in place.

[0023] Furthermore, a corresponding 3D model of the protective device is generated based on the marked inner cavity wall surface, specifically including:

[0024] Measure the normal thickness of each internal cavity reinforcing rib structure and each supporting protrusion structure, and determine the maximum normal thickness. After completion, delete the internal cavity reinforcing rib structure and supporting protrusion structure in the blade 3D model, and only retain the basic geometric model of the internal cavity.

[0025] In the basic geometric model, the edge contour curves of the two end faces of the inner cavity are extracted respectively, and the edge contour curves of the two end faces are offset inward in a normal direction. The offset distance is determined according to the maximum normal thickness.

[0026] The edge contour curves after the two end faces of the inner cavity are offset are used as the boundary curves of the protective device, and a complete three-dimensional model of the protective device is established based on the boundary curves.

[0027] Furthermore, the offset distance is the sum of the maximum normal thickness and the preset thickness, where the preset thickness is 0.3 to 0.8 mm.

[0028] Furthermore, the method for generating a corresponding protective device based on the three-dimensional model of the protective device includes:

[0029] The protective device is manufactured based on a three-dimensional model of the protective device and using a molding method, wherein the molding method is casting, 3D printing or machining.

[0030] Furthermore, the protective device is made of a material resistant to laser damage, which includes one or more of the following: steel, aluminum alloy, titanium alloy, high-temperature alloy, ceramic, graphite, and paraffin wax.

[0031] The beneficial effects of this invention are as follows: The method for generating and protecting the protective device for processing air film pores in hollow blades described in this invention is based on the contour modeling of the inner cavity space of the hollow blade to obtain a three-dimensional model of the protective device. Then, a solid protective device is made based on the three-dimensional model. Before laser processing of the air film pores, the solid protective device is placed in the inner cavity of the hollow blade. After laser processing, the protective device can be removed, thereby avoiding laser damage to the wall, improving the processing quality of the small hole outlet, enabling rapid installation and disassembly, and also improving the yield, quality, and lifespan of high-pressure turbine blades. Attached Figure Description

[0032] Figure 1 This is a schematic flowchart of the method for protecting the air film holes in hollow blades according to an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the three-dimensional model of the blade described in an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the structure of a three-dimensional model of the protective device described in an embodiment of the present invention. Detailed Implementation

[0035] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0036] This invention aims to avoid laser damage to the inner cavity of hollow aero-engine blades during the machining of film cooling holes. It proposes a method for generating a protective device and a protective method for machining film cooling holes on hollow blades. The main technical solutions include: determining a three-dimensional model of the hollow blade to be machined; marking the inner cavity wall surfaces requiring protection in the three-dimensional model of the blade according to the location of the film cooling holes, wherein the marked inner cavity wall surfaces include at least an inner cavity reinforcing rib structure, a support protrusion structure, and the blade cross-section exit shape; generating a corresponding three-dimensional model of the protective device based on the marked inner cavity wall surfaces, and generating a corresponding protective device based on the three-dimensional model of the protective device; before using laser to machine the film cooling holes, inserting the protective device into the inner cavity through the cooling airflow inlet of the hollow blade and fixing it in place.

[0037] Currently, traditional methods for machining film cooling holes on hollow turbine blades mainly include electrical discharge machining (EDM), femtosecond laser drilling, and electro-hydraulic beam drilling. However, during femtosecond laser machining of film cooling holes, the laser beam can cause burns or other damage to the inner wall of the cavity when it irradiates the nearby area after the hole is opened. Therefore, this invention generates a 3D model of a protective device based on the internal cavity structure of the hollow blade and the location of the cavity requiring protection. Then, a physical protective device is generated using methods such as 3D printing. Before machining the film cooling holes on the aero-engine hollow blade, the protective device is placed inside the cavity to protect the inner wall. After machining, the protective device can be removed. This invention not only avoids laser damage to the inner cavity and the machining quality problems at the small hole exit during film cooling hole machining on aero-engine hollow blades, but also allows for the rapid generation of suitable protective devices according to actual needs, resulting in high efficiency.

[0038] Example

[0039] Please see Figure 1 The method for generating a protective device for machining film pores in hollow blades according to an embodiment of the present invention includes the following steps:

[0040] Step 1: Determine the 3D model of the hollow blade to be processed.

[0041] Figure 2 A 3D model of a hollow blade for a high-pressure turbine guide vane of an aero-engine is shown. During manufacturing or repair, the film cooling holes of this type of blade need to be re-machined to restore their corresponding cooling performance. When restoring the film cooling holes using femtosecond laser processing, the inner wall of the blade needs to be protected. In practical applications, the corresponding 3D model of the blade can be found by searching for blades requiring internal cavity laser protection, or a 3D model of the blade can be created using 3D modeling software based on drawings or 3D reverse measurement data.

[0042] Step 2: Mark the inner cavity wall surface that needs to be protected in the three-dimensional model of the blade according to the location of the air film hole to be processed. The marked inner cavity wall surface includes at least the inner cavity reinforcing rib structure, the supporting protrusion structure and the blade cross-section exit shape.

[0043] After obtaining the 3D model of the blade, the locations of the air film vents to be processed in each region of the blade basin are first determined. Based on the axis of the vents to be processed, the locations of internal cavities with potential laser damage are identified. Potentially damaged internal cavity walls are then selected and marked in the 3D model of the blade, while other surface data are deleted or hidden. The marked surfaces include structural information such as the internal cavity reinforcing rib structure, supporting protrusions, and the blade end-face exit morphology.

[0044] Step 3: Generate a three-dimensional model of the corresponding protective device based on the marked inner cavity wall surface, and generate the corresponding protective device based on the three-dimensional model of the protective device.

[0045] In this embodiment, generating the corresponding 3D model of the protective device specifically includes the following steps:

[0046] Step 31: Measure the normal thickness of each inner cavity reinforcing rib structure and each supporting protrusion structure, and determine the maximum normal thickness. After completion, delete the inner cavity reinforcing rib structure and supporting protrusion structure in the blade 3D model, and only retain the basic geometric model of the inner cavity.

[0047] Specifically, the internal cavity wall structure is first simplified by measuring the normal thickness of the internal cavity reinforcing ribs, supporting protrusions, and other structures, recording the maximum normal thickness as 'a', and recording the normal thickness distribution data. After recording, the information of reinforcing ribs and supporting protrusions in the internal cavity 3D model is deleted, retaining only the basic geometric model of the internal cavity.

[0048] Step 32: In the basic geometric model, extract the edge contour curves of the two end faces of the inner cavity respectively, and offset the edge contour curves of the two end faces inward in a normal direction. The offset distance is determined according to the maximum normal thickness.

[0049] Specifically, for the basic geometric model of the inner cavity, two end face positions are selected, the edge contour curves of the end faces are extracted, and then the contour curves of the two end faces are normally offset. The offset direction is inward, and the offset distance is the sum of the maximum normal thickness a and the preset thickness b. In this embodiment, the preset thickness b is 0.3 to 0.8 mm. Figure 3 A schematic diagram of a three-dimensional model of a protective device is shown.

[0050] Step 33: Use the edge contour curves of the two end faces of the inner cavity after offset as the boundary curves of the protective device, and establish a complete three-dimensional model of the protective device based on the boundary curves.

[0051] Specifically, the offset edge curve is used as the boundary curve of the protective block. The side of the protective block is built using UG surface modeling, and the edge curve is sealed to make it a three-dimensional structure, thus completing the creation of the three-dimensional model of the protective device.

[0052] After obtaining the 3D model of the protective device, the physical protective device can be manufactured using molding methods such as casting, 3D printing, and machining. For example, the 3D model of the protective device can be pre-processed and imported into equipment such as 3D printing or machining. The protective device can then be fabricated using the appropriate equipment and post-processed, such as stress-relieving heat treatment, support removal, and surface treatment, to ensure that the dimensions and surface of the finished protective device meet the size and surface quality requirements of the tooling for the blade.

[0053] In this embodiment, the preferred manufacturing material is one with strong resistance to laser damage, such as steel, aluminum alloy, titanium alloy, high-temperature alloy, ceramic, graphite, paraffin wax, etc.

[0054] Please see Figure 1 Based on the above technical solution, this embodiment also proposes a method for protecting the air film holes during hollow blade machining. This method includes all the steps of the above-mentioned method for generating the protective device for air film holes during hollow blade machining, and further includes:

[0055] Step 4: Before using laser processing for air film holes, insert the protective device into the inner cavity through the cooling airflow inlet of the hollow blade and fix it in place.

[0056] In this embodiment, before machining the film cooling holes on the hollow blade of the aero-engine, a protective device is inserted into the blade's inner cavity through the cooling airflow inlet, and the protective block is fixed to the blade edge plate using electrical tape to ensure that the coaxial airflow during laser machining will not cause the protective block to fall off. Then, the geometric parameters of the holes to be machined are determined according to the blade design drawings, reverse engineering of the blade, or image recognition of actual holes. After setting the laser machining parameters, the holes are machined. After machining is completed, the protective device is removed from the inner cavity, and compressed air is used to clean the protective device and the hollow blade.

[0057] In summary, the method for generating and protecting the protective device for processing film pores in hollow blades described in this embodiment is based on contour modeling of the inner cavity space of the hollow blade to obtain a three-dimensional model of the protective device. Then, a solid protective device is manufactured based on the three-dimensional model. The manufacturing efficiency of the protective device is high. Before laser processing of the film pores, the solid protective device is placed in the inner cavity of the hollow blade. After laser processing, the protective device can be removed, thereby avoiding laser damage to the wall and problems with the processing quality of the small hole outlet. It can be quickly installed and disassembled, and also improves the yield, quality and life of high-pressure turbine blades.

[0058] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for generating a protective device for machining film pores in hollow blades, characterized in that, The method includes: Determine the 3D model of the hollow blade to be processed; According to the location of the air film hole to be processed, mark the inner cavity wall surface that needs to be protected in the three-dimensional model of the blade. The marked inner cavity wall surface includes at least the inner cavity reinforcing rib structure, the supporting protrusion structure and the blade cross section exit shape. Generate a corresponding 3D model of the protective device based on the marked inner cavity wall surface, and generate the corresponding protective device based on the 3D model of the protective device. A 3D model of the corresponding protective device is generated based on the marked inner cavity wall surface, specifically including: Measure the normal thickness of each internal cavity reinforcing rib structure and each supporting protrusion structure, and determine the maximum normal thickness. After completion, delete the internal cavity reinforcing rib structure and supporting protrusion structure in the blade 3D model, and only retain the basic geometric model of the internal cavity. In the basic geometric model, the edge contour curves of the two end faces of the inner cavity are extracted respectively, and the edge contour curves of the two end faces are offset inward in a normal direction. The offset distance is determined according to the maximum normal thickness. The edge contour curves after the two end faces of the inner cavity are offset are used as the boundary curves of the protective device, and a complete three-dimensional model of the protective device is established based on the boundary curves.

2. The method for generating a protective device for machining film pores in hollow blades as described in claim 1, characterized in that, The offset distance is the sum of the maximum normal thickness and the preset thickness, where the preset thickness is 0.3~0.8mm.

3. The method for generating a protective device for machining film pores in hollow blades as described in claim 1, characterized in that, The method for generating a corresponding protective device based on the three-dimensional model of the protective device includes: The protective device is manufactured based on a three-dimensional model of the protective device and using a molding method, wherein the molding method is casting, 3D printing or machining.

4. The method for generating a protective device for machining film pores in hollow blades as described in claim 3, characterized in that, The protective device is made of a material resistant to laser damage, which includes one or more of the following: steel, aluminum alloy, titanium alloy, high-temperature alloy, ceramic, graphite, and paraffin wax.

5. A method for protecting air film holes during hollow blade machining, characterized in that, The method includes: Determine the 3D model of the hollow blade to be processed; According to the location of the air film hole to be processed, mark the inner cavity wall surface that needs to be protected in the three-dimensional model of the blade. The marked inner cavity wall surface includes at least the inner cavity reinforcing rib structure, the supporting protrusion structure and the blade cross section exit shape. Generate a corresponding 3D model of the protective device based on the marked inner cavity wall surface, and generate the corresponding protective device based on the 3D model of the protective device. Before using laser processing for air film holes, the protective device is inserted into the inner cavity through the cooling airflow inlet of the hollow blade and fixed in place; A 3D model of the corresponding protective device is generated based on the marked inner cavity wall surface, specifically including: Measure the normal thickness of each internal cavity reinforcing rib structure and each supporting protrusion structure, and determine the maximum normal thickness. After completion, delete the internal cavity reinforcing rib structure and supporting protrusion structure in the blade 3D model, and only retain the basic geometric model of the internal cavity. In the basic geometric model, the edge contour curves of the two end faces of the inner cavity are extracted respectively, and the edge contour curves of the two end faces are offset inward in a normal direction. The offset distance is determined according to the maximum normal thickness. The edge contour curves after the two end faces of the inner cavity are offset are used as the boundary curves of the protective device, and a complete three-dimensional model of the protective device is established based on the boundary curves.

6. The method for protecting the air film pores during hollow blade machining as described in claim 5, characterized in that, The offset distance is the sum of the maximum normal thickness and the preset thickness, where the preset thickness is 0.3~0.8mm.

7. The method for protecting the air film pores during hollow blade machining as described in claim 5, characterized in that, The method for generating a corresponding protective device based on the three-dimensional model of the protective device includes: The protective device is manufactured based on a three-dimensional model of the protective device and using a molding method, wherein the molding method is casting, 3D printing or machining.

8. The method for protecting the air film pores during hollow blade machining as described in claim 7, characterized in that, The protective device is made of a material resistant to laser damage, which includes one or more of the following: steel, aluminum alloy, titanium alloy, high-temperature alloy, ceramic, graphite, and paraffin wax.

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