Combined machining method for dustpan-shaped air film hole of double-wall turbine blade

Abstract

The invention relates to the technical field of aero-engines, and discloses a combined machining method for a dustpan-shaped film hole of a double-wall turbine blade, a cylindrical section is machined through electro-hydraulic beams, a special-shaped section is machined through laser, the distance between a laser focus and an inner layer wall in the machining process is increased, and the risk that the inner layer wall is damaged by the laser can be effectively reduced; and meanwhile, an inverted circular truncated cone of the laser processing model is utilized, the back gouging effect on the junction position of the cylindrical section and the special-shaped section can be achieved, and no step exists at the tool connecting position. Besides, due to the overflow effect of the electro-hydraulic beam machining mode, in the process of machining the cylindrical section through the electro-hydraulic beams, chamfers can be naturally generated at the inner hole openings of the air film holes, the problem of stress concentration of the inner hole openings of the air film holes can be effectively solved, and therefore the strength of the air film holes is improved.

Description

Technical Field

[0001] The invention relates to the technical field of aeroengines and discloses a composite processing method for a dustpan-shaped air film hole of a double-wall turbine blade. Background Art

[0002] As the temperature before the aircraft engine turbine continues to rise, the temperature of the combustion gas washing the surface of the turbine blades is also getting higher and higher. The traditional cylindrical film holes can no longer meet the blade cooling needs. The dustpan-type film holes are gradually being widely used because of their greatly improved cooling efficiency.

[0003] The dustpan-type air film hole includes a special-shaped section near the outer surface of the double-wall turbine blade and a cylindrical section at the bottom of the special-shaped section. This structure cannot be directly formed by electro-hydraulic beam processing, and electro-spark processing will cause the wall surface to remelt and reduce the strength of the air film hole. Therefore, the dustpan-type air film hole of the single-wall turbine blade is generally processed by ultrafast laser, and then the inner and outer edges of the air film hole are rounded by liquid abrasive flow to improve the strength of the air film hole. For double-wall turbine blades, due to the very narrow cavity between the inner and outer walls, laser hole making has a greater risk of wall damage; and the shape of the cold air channel inside the double-wall turbine blade is complicated, and the liquid abrasive flow is not only difficult to establish sufficient pressure to achieve orifice rounding, but also likely to cause serious wear to the inner cavity structures such as the flow column and the impact hole, reducing the strength of the blade. At the same time, the abrasive in the liquid abrasive flow is difficult to completely remove in the complex inner cavity, so the dustpan-type air film hole faces great difficulties in the processing of double-wall turbine blades. Summary of the invention

[0004] The purpose of the present invention is to provide a composite processing method for a double-wall turbine blade dustpan-type air film hole, which can effectively reduce the risk of laser damage to the inner wall and effectively reduce the problem of stress concentration at the hole mouth of the air film hole, thereby improving the strength of the air film hole.

[0005] In order to achieve the above technical effects, the technical solution adopted by the present invention is:

[0006] A composite processing method for a dustpan-shaped air film hole of a double-wall turbine blade, comprising:

[0007] The dustpan-shaped air film pore structure on the outer wall of the double-wall turbine blade is decomposed into a special-shaped segment close to the outer surface of the double-wall turbine blade and a cylindrical segment at the bottom of the special-shaped segment.

[0008] The double-wall turbine blade is clamped and fixed, and according to the size parameters of the cylindrical segment of the air film hole to be processed, an electro-hydraulic beam is used to perform through-hole processing on the outer wall of the double-wall turbine blade to obtain a through-hole with a cylindrical segment;

[0009] Filling the inside of the double-wall turbine blade with laser protection material, using an image recognition device to collect the cross-sectional profile curve of the through hole, obtaining the position of the central axis of the through hole, and analyzing to obtain the coordinates of the intersection of the central axis of the through hole and the outer surface of the double-wall turbine blade;

[0010] Constructing a three-dimensional model of a dustpan-shaped air film hole special-shaped segment, establishing an inverted truncated cone model on the bottom surface of the three-dimensional model of the special-shaped segment, wherein the larger bottom surface of the truncated cone model coincides with the bottom surface of the three-dimensional model of the special-shaped segment, so that the three-dimensional model of the special-shaped segment and the truncated cone model are combined to form an initial model of the special-shaped segment;

[0011] Cutting out the concentric cylinders of the through hole on the initial model, wherein the diameter of the concentric cylinders is 0.6 to 0.8 times the diameter of the through hole, and the remaining structure is used as the laser processing model of the special-shaped segment;

[0012] The laser processing model is cut by a plane perpendicular to the axial direction of the through hole, and a laser processing path is generated according to each cut structure, and laser processing of the special-shaped segment of the air film hole is completed according to the laser processing path.

[0013] Furthermore, before electro-hydraulic beam processing, the double-walled turbine blades are filled with electro-hydraulic beam protective material, and after the electro-hydraulic beam processing is completed and before the laser protective material is added to the inside of the double-walled turbine blades, the electro-hydraulic beam protective material inside the double-walled turbine blades is removed and the inside of the double-walled turbine blades is cleaned.

[0014] Furthermore, the method of using an image recognition device to collect the cross-sectional contour curve of the through hole and obtaining the central axis position of the through hole includes: using an image recognition device to collect image information of the air film hole to be processed, and obtaining the central axis position of the through hole based on the color difference between the laser protection material and the outer wall matrix of the double-wall turbine blade.

[0015] Furthermore, an opaque tape is pasted on the through hole of the air film hole to be processed, and a ranging laser beam located at the central axis of the through hole is used to irradiate the opaque tape to obtain the coordinates of the intersection of the central axis of the through hole and the outer surface of the double-wall turbine blade.

[0016] Furthermore, the thickness of the tape is less than 0.05 mm.

[0017] Furthermore, after the laser processing is completed, the laser protection material inside the double-wall turbine blade is removed, and the hole opening of the special-shaped section close to the outer surface is magnetically ground to obtain a special-shaped section air film hole structure with a rounded structure.

[0018] Furthermore, the diameter of the magnetic needle selected during the magnetic grinding process is larger than the diameter of the cylindrical section of the air film hole.

[0019] Compared with the prior art, the present invention has the following beneficial effects: the present invention increases the distance between the laser focus and the inner wall during the processing by electro-hydraulic beam processing of the cylindrical segment and laser processing of the special-shaped segment, which can effectively reduce the risk of laser damage to the inner wall; at the same time, the inverted truncated cone of the laser processing model can be used to clean the intersection of the cylindrical segment and the special-shaped segment, so that there will be no steps at the cutting position. In addition, due to the overflow effect of the electro-hydraulic beam processing method, the hole opening of the air film hole will naturally be chamfered during the electro-hydraulic beam processing of the cylindrical segment, which can effectively reduce the problem of stress concentration at the hole opening of the air film hole, thereby improving the strength of the air film hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a flow chart of the composite processing method of the dustpan-shaped air film hole in Example 1 or 2;

[0021] Figure 2 It is a schematic diagram of the decomposition structure of the dustpan-type air film hole in Example 1 or 2;

[0022] Figure 3 Schematic diagram of the through hole structure with cylindrical segments processed on the outer wall in Example 1 or 2;

[0023] Figure 4 It is a schematic diagram of the structure of the laser processing model of the special-shaped segment in Example 1 or 2;

[0024] Figure 5 Schematic diagram of the laser processing area in Example 1 or 2;

[0025] Figure 6 Schematic diagram of the dustpan-shaped air film hole structure processed on the outer wall in Example 1 or 2;

[0026] Among them, 1. outer wall; 2. special-shaped segment; 3. cylindrical segment; 4. through hole; 5. frustum model; 6. concentric cylinder; 7. laser processing area. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the embodiments and drawings. However, it should not be understood that the scope of the above subject matter of the present invention is limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0028] Example 1

[0029] See also Figure 1-Figure 6 , a composite processing method for a double-wall turbine blade dustpan-shaped air film hole, comprising:

[0030] The dustpan-shaped air film hole structure on the outer wall 1 of the double-wall turbine blade is decomposed into a special-shaped section 2 close to the outer surface of the double-wall turbine blade and a cylindrical section 3 located at the bottom of the special-shaped section 2;

[0031] The double-wall turbine blade is clamped and fixed, and according to the size parameters of the cylindrical section 3 of the air film hole to be processed, an electro-hydraulic beam is used to process a through hole 4 on the outer wall 1 of the double-wall turbine blade to obtain a through hole 4 with a cylindrical section 3;

[0032] Fill the double-wall turbine blade with laser protection material, use an image recognition device to collect the cross-sectional profile curve of the through hole 4, obtain the central axis position of the through hole 4, and analyze and obtain the intersection coordinates of the central axis of the through hole 4 and the outer surface of the double-wall turbine blade;

[0033] Construct a three-dimensional model of a dustpan-shaped air film hole profiled section 2, and establish an inverted truncated cone model 5 on the bottom surface of the three-dimensional model of the profiled section 2, wherein the larger bottom surface of the truncated cone model 5 coincides with the bottom surface of the three-dimensional model of the profiled section 2, so that the three-dimensional model of the profiled section 2 and the truncated cone model 5 are combined to form an initial model of the profiled section 2;

[0034] A concentric cylinder of the through hole 4 is cut out from the initial model, and the diameter of the concentric cylinder is 0.6 to 0.8 times the diameter of the through hole 4, and the remaining structure is used as a laser processing model of the special-shaped segment 2;

[0035] The laser processing model is cut by a plane perpendicular to the axial direction of the through hole 4, and a laser processing path is generated according to each cut structure. According to the laser processing path, the laser processing of the special-shaped segment 2 of the air film hole is completed.

[0036] In this embodiment, the distance between the laser focus and the inner wall during the processing is increased by electro-hydraulic beam processing of the cylindrical segment 3 and laser processing of the special-shaped segment 2, which can effectively reduce the risk of laser damage to the wall; at the same time, the inverted truncated cone of the laser processing model can be used to clean the intersection of the cylindrical segment 3 and the special-shaped segment 2, so that there will be no steps at the cutting position. In addition, due to the overflow effect of the electro-hydraulic beam processing method, during the electro-hydraulic beam processing of the cylindrical segment 3, the hole opening of the air film hole will naturally be chamfered, which can effectively reduce the problem of stress concentration at the hole opening of the air film hole, thereby improving the strength of the air film hole.

[0037] Example 2

[0038] See also Figure 1-Figure 6 This embodiment takes the processing of the dustpan-shaped air film hole of the outer wall 1 of a certain type of double-wall turbine blade as an example to describe in detail the composite processing method of the dustpan-shaped air film hole of the double-wall turbine blade of the present invention. The specific processing steps are as follows:

[0039] Step 1: Decompose the dustpan-shaped air film hole structure on the outer wall 1 of the double-wall turbine blade into a special-shaped section 2 close to the outer surface of the double-wall turbine blade and a cylindrical section 3 located at the bottom of the special-shaped section 2;

[0040] Step 2: clamp and fix the double-wall turbine blade, and according to the size parameters of the cylindrical section 3 of the air film hole to be processed, use an electro-hydraulic beam to process the through hole 4 on the outer wall 1 of the double-wall turbine blade to obtain the through hole 4 with the cylindrical section 3;

[0041] In this embodiment, step 2 includes the following sub-steps:

[0042] S201: Filling the inner cavity of the blade with special electro-hydraulic beam protective material for electro-hydraulic beam hole making;

[0043] S202: The blade position is completely constrained by tenon or six-point positioning fixtures to achieve clamping and fixing of the double-wall turbine blade, and a three-dimensional space coordinate system is established in which the Z axis coincides with the stacking axis of the double-wall turbine blade.

[0044] S203: performing electro-hydraulic beam processing of the dustpan-shaped air film hole cylindrical section 3;

[0045] S204: Clean the electro-hydraulic beam protective material in the inner cavity of the blade.

[0046] In this step, due to the overflow effect of the electro-hydraulic jet machining method, during the electro-hydraulic jet machining of the cylindrical segment 3, the hole opening of the air film hole will naturally be chamfered, which can effectively reduce the problem of stress concentration at the hole opening of the air film hole, thereby improving the strength of the air film hole.

[0047] Step 3: Fill the double-wall turbine blade with laser protection material, and use an image recognition device to collect the cross-sectional profile curve of the through hole 4 to obtain the central axis position of the through hole 4;

[0048] In this embodiment, step 2 includes the following sub-steps:

[0049] S301: Filling the inner cavity of the blade with laser protection material specially used for laser hole making;

[0050] S302: Fully constrain the blade position by using tenon teeth or six-point positioning fixtures;

[0051] S303: using an image recognition device to collect image information of the air film hole to be processed, and obtaining the central axis position of the through hole 4 based on the color difference between the laser protection material and the outer wall 1 matrix of the double-wall turbine blade.

[0052] Step 4: Paste a thin layer (thickness less than 0.05mm) of opaque tape on the surface of the blade to cover the outer opening of the through hole 4. Scan the light beam along the central axis identified in step S303. The intersection of the light beam and the tape is the center coordinate of the through hole 4. Mark the center coordinate of the through hole 4 for all air film holes that need to be processed in this way.

[0053] Step five, construct a three-dimensional model of the dustpan-shaped air film hole special-shaped segment 2, and establish an inverted truncated cone model 5 on the bottom surface of the three-dimensional model of the special-shaped segment 2. The larger bottom surface of the truncated cone model 5 coincides with the bottom surface of the three-dimensional model of the special-shaped segment 2, so that the three-dimensional model of the special-shaped segment 2 and the truncated cone model 5 are combined to form the initial model of the special-shaped segment 2; the setting of the truncated cone model 5 is used to realize the function of cleaning the root at the junction of the cylindrical segment 3 and the special-shaped segment 2.

[0054] In this embodiment, since there are always processing errors in the processing process, when the diameter of the electro-hydraulic beam processed through hole 4 is too small, the bottom surface of the laser processed special-shaped section 2 cannot be connected to the junction position. At this time, the existence of the frustum model 5 can achieve the effect of smoothly connecting the laser processing area to the junction position without producing an obvious tool connection table.

[0055] In this embodiment, the smaller bottom radius of the truncated cone model 5 may also be restricted, for example, the smaller bottom diameter of the truncated cone model is not greater than 0.6 times the diameter of the through hole.

[0056] Step 6: Cut off the concentric cylinder of the through hole 4 on the initial model, and the diameter of the concentric cylinder is 0.6 to 0.8 times the diameter of the through hole 4. The remaining structure is used as the laser processing model of the special-shaped segment 2 (such as Figure 5 The laser processing area 7 is shown.

[0057] Step seven, use a plane perpendicular to the axial direction of the through hole 4 to cut the laser processing model, and generate a laser processing path according to each cut structure, and according to the laser processing path, complete the laser processing of the special-shaped segment 2 of the air film hole, and measure the aperture of the blade air film hole. After meeting the size requirements, use a magnetic needle to perform magnetic grinding on the outer opening of the blade special-shaped hole.

[0058] In the present embodiment, the outer hole opening is rounded by magnetic grinding, and the inner hole opening of the air film hole is chamfered during the electro-hydraulic beam processing of the cylindrical segment 3. Therefore, the chamfers (circles) produced on the inner and outer hole openings of the dustpan-shaped air film hole formed by the composite processing method of the present invention can effectively reduce the stress concentration at the hole opening position, and can further improve the strength of the air film hole.

[0059] In the present embodiment, the diameter of the magnetic needle used in the magnetic grinding process is larger than the diameter of the cylindrical section 3 of the air film hole, ensuring that the magnetic needle will not enter the inner cavity of the blade, thus avoiding wear on the inner cavity structure and not facing the problem of difficult removal of abrasives.

[0060] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite processing method for a double-wall turbine blade dustpan-shaped air film hole, characterized in that: include: The dustpan-shaped air film pore structure on the outer wall of the double-wall turbine blade is decomposed into a special-shaped segment close to the outer surface of the double-wall turbine blade and a cylindrical segment at the bottom of the special-shaped segment. The double-wall turbine blade is clamped and fixed, and according to the size parameters of the cylindrical segment of the air film hole to be processed, an electro-hydraulic beam is used to perform through-hole processing on the outer wall of the double-wall turbine blade to obtain a through-hole with a cylindrical segment; Filling the inside of the double-wall turbine blade with laser protection material, using an image recognition device to collect the cross-sectional profile curve of the through hole, obtaining the position of the central axis of the through hole, and analyzing to obtain the coordinates of the intersection of the central axis of the through hole and the outer surface of the double-wall turbine blade; Constructing a three-dimensional model of a dustpan-shaped air film hole special-shaped segment, establishing an inverted truncated cone model on the bottom surface of the three-dimensional model of the special-shaped segment, wherein the larger bottom surface of the truncated cone model coincides with the bottom surface of the three-dimensional model of the special-shaped segment, so that the three-dimensional model of the special-shaped segment and the truncated cone model are combined to form an initial model of the special-shaped segment; Cutting out the concentric cylinders of the through hole on the initial model, wherein the diameter of the concentric cylinders is 0.6 to 0.8 times the diameter of the through hole, and the remaining structure is used as the laser processing model of the special-shaped segment; The laser processing model is cut by a plane perpendicular to the axial direction of the through hole, and a laser processing path is generated according to each cut structure, and laser processing of the special-shaped segment of the air film hole is completed according to the laser processing path.

2. The composite processing method of the dustpan-shaped air film hole of the double-wall turbine blade according to claim 1 is characterized in that: Before electro-hydraulic beam machining, the electro-hydraulic beam protective material is filled into the double-walled turbine blade, and after the electro-hydraulic beam machining is completed and before the laser protective material is added into the double-walled turbine blade, the electro-hydraulic beam protective material inside the double-walled turbine blade is removed and the inside of the double-walled turbine blade is cleaned.

3. The composite processing method of the dustpan-shaped air film hole of the double-wall turbine blade according to claim 1 is characterized in that: The method of using an image recognition device to collect the cross-sectional contour curve of a through hole and obtaining the central axis position of the through hole includes: using an image recognition device to collect image information of the air film hole to be processed, and obtaining the central axis position of the through hole based on the color difference between the laser protection material and the outer wall matrix of the double-wall turbine blade.

4. The composite processing method of the dustpan-shaped air film hole of the double-wall turbine blade according to claim 3 is characterized in that: An opaque tape is pasted on the through hole of the air film hole to be processed, and a ranging laser beam located on the central axis of the through hole is used to irradiate the opaque tape to obtain the coordinates of the intersection of the central axis of the through hole and the outer surface of the double-wall turbine blade.

5. The composite processing method of the dustpan-shaped air film hole of the double-wall turbine blade according to claim 4 is characterized in that: The tape thickness is less than 0.05mm.

6. The composite processing method of the dustpan-shaped air film hole of the double-wall turbine blade according to claim 1 is characterized in that: After the laser processing is completed, the laser protection material inside the double-wall turbine blade is removed, and the hole opening of the special-shaped section close to the outer surface is magnetically ground to obtain a special-shaped section air film hole structure with a rounded structure.

7. The composite processing method of the dustpan-shaped air film hole of the double-wall turbine blade according to claim 6 is characterized in that: The diameter of the magnetic needle selected during the magnetic grinding process is larger than the diameter of the cylindrical section of the air film hole.

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