Method and equipment for manufacturing fatigue crack blade

Abstract

The invention relates to a method and equipment for manufacturing a fatigue crack blade. The method for manufacturing the fatigue crack blade comprises the following steps that a sample is cut out, heat treatment is conducted on the sample, and a notch is prefabricated in the surface of the sample through milling; placing the sample on a clamp, installing the clamp on a fatigue testing machine, and clamping a measuring system on the sample; performing a bending fatigue experiment through a fatigue testing machine to prefabricate a fatigue crack; the measuring device displays the fatigue crack length in real time, and after the fatigue crack length reaches the preset fatigue crack length, the fatigue testing machine stops running; a sample is machined into a blade shape through linear cutting, a prefabricated notch is cut off, fatigue cracks are reserved, and the blade with the fatigue cracks is installed on a blade disc. The method and the equipment for manufacturing the fatigue crack blade have the advantage that the fatigue crack is more real than that of an existing linear cutting notch.

Description

Technical Field

[0001] The invention relates to the field of fatigue crack blades, in particular to a method for manufacturing fatigue crack blades and equipment thereof. Background Art

[0002] Compressor blades are key components that rotate and affect the safety and efficiency of aircraft engines, and they play an important role in improving the comprehensive performance of aircraft engines. Under high speed, high load and complex working environment, fatigue cracks are prone to occur in blades. If the cracks are not discovered and treated in time, the fatigue cracks will continue to expand under the action of cyclic stress, leading to serious faults such as compressor blade breakage, causing major safety accidents, casualties and significant economic losses. It can be seen that fatigue cracks threaten the safe operation of aircraft engines, and accurate identification of their faults is an important way to ensure the safe operation of aircraft engines.

[0003] Vibration-based structural damage identification technology has the advantages of real-time, high efficiency, and strong environmental adaptability, and has been widely used in the field of crack fault diagnosis. In order to reliably identify compressor blade crack faults using vibration characteristics, researchers have conducted extensive research to seek vibration characteristics that are more sensitive to crack damage. Experimental research is an important research method and an important basis for evaluating the effectiveness of theoretical research. Due to the limitations of various conditions such as site, cost, and technology, it is extremely difficult for researchers to directly use aircraft engines to conduct crack blade vibration experiments. At present, aircraft engine simulation test benches are generally used to conduct experiments to study the vibration characteristics of crack faults. However, in these experimental processes, it is currently found that blade cracks in all literature are not actual fatigue cracks, but fatigue cracks simulated by wire cutting notches, which is inconsistent with the actual fatigue crack blades. From the existing literature, it can be seen that in "Fatigue and Fracture" compiled by Chen Chuanyao of Huazhong University of Science and Technology in January 2002, Section 9.2 describes the crack closure phenomenon and theory in detail. Studies have shown that fatigue cracks will have obvious crack closure phenomena, which cannot be simulated by wire cutting notches. Some scholars have stated in the literature that wire cutting notches can introduce large errors and affect the accuracy of test results. For example, the journal "JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS" published an article by Gudmundson in 2010 titled "The dynamic behavior of slender structures with cross-sectional cracks". The article experimentally studied the effect of fatigue crack closure on beam vibration, and the results showed that the analysis results without considering the effect of crack closure were different from the experimental results. However, since crack blade vibration test involves cross-fields such as fatigue crack extension and vibration, no effective method has been proposed to make fatigue crack blades. Summary of the invention

[0004] Based on this, an object of the present invention is to provide a method for manufacturing a fatigue crack blade.

[0005] A method for making a fatigue crack blade comprises the following steps: cutting out a sample, first heat treating the sample, and then prefabricating a notch on one of the surfaces of the sample by milling or wire cutting; placing the sample on a fixture, installing the fixture on a fatigue testing machine, and clamping a measuring system on the sample; prefabricating fatigue cracks by performing a bending fatigue test on the fatigue testing machine; the measuring device displays the fatigue crack length in real time, and determines whether the fatigue crack length reaches a preset fatigue crack length, and when the fatigue testing machine reaches the preset fatigue crack length, the fatigue testing machine stops running; processing the sample into a blade shape by wire cutting or milling, removing the prefabricated notch during the cutting process, retaining the fatigue crack, and installing the fatigue cracked blade on a blade disk.

[0006] The method for making fatigue cracked blades described in the present invention can prefabricate real fatigue cracks by using a bending fatigue test. Compared with existing wire-cut notches, fatigue cracks are more consistent with actual cracks produced in engineering. The fatigue cracked blades are installed on a blade disk, and a rotating cracked blade simulation operation test is carried out, which can accurately simulate the crack breathing behavior, is conducive to studying and analyzing the vibration characteristics of faults caused by actual fatigue cracks, provides an experimental basis for extracting vibration characteristics that are sensitive to crack damage, and effectively develops online diagnostic methods and technologies based on vibration identification of blade fatigue cracks.

[0007] Furthermore, the notch is a straight-through notch produced by wire cutting, and the radius of curvature at the root of the notch is less than or equal to 0.08 mm.

[0008] Furthermore, the notch is a milled herringbone notch, and the curvature radius of the notch root is less than or equal to 0.25 mm.

[0009] Furthermore, by inputting the set crack length on the fatigue testing machine, inputting the stress ratio, maximum loading force, frequency and other parameters, the length of the preset fatigue crack is adjusted.

[0010] Furthermore, fatigue crack blades are processed by milling the specimens containing fatigue cracks, wherein the fatigue crack blades include a blade base and a blade body, the fatigue crack is located in the middle of the blade body, and a blade fixing hole is processed on the blade base by drilling; the fatigue crack blades are installed on the blade disk through the blade fixing holes, and crack-free blades are also evenly installed on the blade disk; the number of fatigue crack blades on the blade disk is selected according to experimental needs, and different numbers of fatigue crack blades are installed at different positions.

[0011] The present invention also provides a device for making fatigue crack blades, including a fixture, a fatigue testing machine and a measuring system; the fixture is used to clamp the sample, the fixture is installed on the fatigue testing machine, and the fatigue testing machine is used to perform a bending fatigue test to prefabricate fatigue cracks; the measuring system is used to measure the length of the fatigue crack.

[0012] Furthermore, the fixture is a three-point bending fixture, including a single-point support component and a double-point support component, the single-point support component including a first testing machine chuck clamping cylinder, a connecting block, a first side plate and a support pin, one end of the connecting block is fixed on the first testing machine chuck clamping cylinder, the front end of the connecting block is provided with a semi-cylindrical concave surface, both ends of the support pin are fixed to the first side plate by screws, and the support pin shaft body is installed on the semi-cylindrical concave surface; the double-point support component includes a second testing machine chuck clamping cylinder, a supporting platform, a supporting connecting seat, two L-shaped support blocks, a second side plate and a support pin, the support connecting seat is fixed on the second testing machine chuck clamping cylinder, the supporting platform is fixed on the supporting connecting seat, two L-shaped support blocks are relatively arranged on the supporting platform, the front end of the L-shaped support block is provided with a semi-cylindrical concave surface, both ends of the support pin are fixed to the second side plate by screws, and the support pin shaft body is installed on the semi-cylindrical concave surface.

[0013] Furthermore, the fixture is a four-point bending fixture, including two double-point support components, the double-point support components include a second testing machine chuck clamping cylinder, a support platform, a support connecting seat, two L-shaped support blocks, a second side plate and a support pin, the support connecting seat is fixed on the second testing machine chuck clamping cylinder, the support platform is fixed on the support connecting seat, two L-shaped support blocks are relatively arranged on the support platform, a semi-cylindrical concave surface is provided at the front end of the L-shaped support block, both ends of the support pin are fixed to the second side plate by screws, and the support pin shaft body is installed on the semi-cylindrical concave surface.

[0014] Furthermore, the measurement system is a COD gauge measurement system, comprising a COD gauge, and the COD gauge is used to be clamped on a sample to measure the fatigue crack length on the sample.

[0015] Furthermore, the measuring system is an industrial video microscope, which is installed at an appropriate position to measure fatigue cracks on a sample.

[0016] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a flow chart of manufacturing a fatigue crack blade according to Embodiment 1 of the present invention;

[0018] Figure 2 This is a flow chart of manufacturing a fatigue crack blade according to Embodiment 2 of the present invention;

[0019] Figure 3 It is a structural schematic diagram of the three-point bending fixture of the present invention;

[0020] Figure 4 It is a structural schematic diagram of a single-point support component of the present invention;

[0021] Figure 5 It is a structural schematic diagram of a double-point support component of the present invention;

[0022] Figure 6 It is a structural schematic diagram of the four-point bending fixture of the present invention;

[0023] Figure 7 It is a schematic structural diagram of a sample with a notch according to the present invention;

[0024] Figure 8 It is a schematic structural diagram of a sample processed with fatigue cracks according to the present invention;

[0025] Fig. 9 It is a schematic diagram of notching a sample processed with fatigue cracks according to the present invention;

[0026] Fig.10 It is a schematic diagram of the structure of a sample with fatigue crack after cutting a notch according to the present invention;

[0027] Fig.11 It is a structural schematic diagram of a fatigue crack blade of the present invention;

[0028] Fig.12 It is a schematic structural diagram of a blade disk with fatigue crack blades according to the present invention.

[0029] Markings in the figure: 1, specimen; 2, single-point support component; 3, double-point support component; 4, COD gauge; 5, fatigue crack blade; 6, blade disk; 7, crack-free blade; 10, notch; 100, fatigue crack;

[0030] 21. The first testing machine chuck clamps the cylinder; 22. The connecting block; 23. The side plate; 24. The supporting pin; 25. The screw;

[0031] 31. The second testing machine chuck clamps the cylinder; 32. The supporting platform; 33. The supporting connecting seat; 34. The L-shaped supporting block; 35. The concave through groove; 36. The inverted T-shaped bolt; 37. The locking nut;

[0032] 51. Blade base; 52. Blade body; 53. Blade fixing hole. DETAILED DESCRIPTION

[0033] Example 1

[0034] Please refer to Figure 1-12 The equipment for making fatigue crack blades of the present invention includes a fixture, a fatigue testing machine and a measuring system.

[0035] The fixture is installed on the fatigue testing machine, and the fixture is used to clamp the sample 1. In this embodiment, the fixture is a three-point bending fixture, and the three-point bending fixture includes a single-point support component 2 and a double-point support component 3.

[0036] The single-point support component includes a first testing machine chuck clamping cylinder 21, a connecting block 22, a first side plate 23 and a support pin 24. One end of the connecting block 22 is fixed to the first testing machine chuck clamping cylinder 21. The front end of the connecting block 22 is provided with a semi-cylindrical concave surface. Both ends of the support pin 24 are fixed to the first side plate 23 by screws 25. The shaft body of the support pin 24 is installed on the semi-cylindrical concave surface.

[0037] The double-point support component 3 includes a second testing machine chuck clamping cylinder 31, a support platform 32, a support connection seat 33, two L-shaped support blocks 34, a second side plate, and a support pin 24. The support connection seat 33 is fixed on the second testing machine chuck clamping cylinder 31, the support platform 32 is fixed on the support connection seat 33, and two L-shaped support blocks 34 are arranged on the support platform 32. The front end of the L-shaped support block 34 is provided with a semi-cylindrical concave surface, and the two ends of the support pin 24 are fixed on the second side plate by screws 25. The shaft body of the support pin 24 is installed on the semi-cylindrical concave surface. When clamping the sample, the support pin 24 of the single-point support component 2 is against the upper end of the sample 1, and the support pin 24 of the double-point support component 3 is supported on the lower end of the sample 1.

[0038] Furthermore, the support platform 32 is provided with two concave through grooves 35 along the axis, and the bottom end of the L-shaped support block 34 is fixed in the concave through groove 35 by an inverted T-shaped bolt 36, and the inverted T-shaped bolt 36 is equipped with a locking nut 37, and the head of the inverted T-shaped bolt 36 is installed in the concave barrel groove 35. By tightening the locking nut 37, the top surface of the head of the inverted T-shaped bolt 36 is in close contact with the surface of the concave through groove 35, and the locking nut 37 is in close contact with the bottom end surface of the L-shaped support block 34.

[0039] In another embodiment, the fixture is a four-point bending fixture, which includes two double-point supporting components 3. When clamping the sample 1, one double-point supporting component 3 is supported on the upper end of the sample 1, and the other double-point supporting component 3 is supported on the lower end of the sample 1.

[0040] The fatigue testing machine includes an upper chuck and a lower chuck, wherein the upper chuck clamps the single-point support component 2, and the lower chuck clamps the double-point support component 3. The fatigue testing machine uses a fatigue testing machine including a crack extension test function software package, such as an MTS810 fatigue testing machine, and performs a three-point bending fatigue test on the fatigue testing machine to prefabricate fatigue cracks. The prefabricated length of the fatigue crack is adjusted by inputting a set crack length, stress ratio, maximum loading force, frequency and other parameters on the fatigue testing machine.

[0041] The measurement system is a COD gauge monitoring system, including a COD gauge 4, which is a common COD gauge 4 in the prior art. The COD gauge 4 is clamped on the sample 1, and the fatigue crack length is displayed in real time through the COD gauge 4; the COD gauge detection system is connected to the test fatigue machine, and a signal is sent to the fatigue testing machine through the COD gauge 4. During the fatigue crack prefabrication process, when the preset fatigue crack length is reached, the fatigue testing machine automatically stops running.

[0042] The method for manufacturing a fatigue crack blade of the present invention comprises the following steps:

[0043] S10: Cut out a rectangular parallelepiped sample 1, perform heat treatment on the sample 1, and then prefabricate a notch 10 on one surface of the sample 1 by milling or wire cutting.

[0044] In this embodiment, the notch 10 is a straight-through notch 10 cut by wire cutting, and the curvature radius of the root of the notch 10 is less than or equal to 0.08 mm. The notch 10 can also be a herringbone notch 10 cut by milling, and the curvature radius of the root of the notch 10 is less than or equal to 0.25 mm.

[0045] S20: placing the sample 1 on the fixture, installing the fixture on the fatigue testing machine, and clamping the COD gauge 4 on the sample 1.

[0046] S30: Prefabricate fatigue cracks by performing a three-point bending fatigue test on a fatigue testing machine.

[0047] The prefabricated length of the fatigue crack is adjusted by inputting the set crack length, stress ratio, maximum loading force, frequency and other parameters on the fatigue testing machine.

[0048] S40: The COD gauge 4 displays the fatigue crack length in real time and determines whether the fatigue crack length reaches a preset fatigue crack length. If the length reaches a preset fatigue crack length, the fatigue testing machine stops running.

[0049] S50: The fatigue testing machine stops running.

[0050] S60: The sample 1 is processed into a blade shape by wire cutting or milling, and the prefabricated notch 10 is cut off during the cutting process, and the fatigue crack 100 is retained, and the blade containing the fatigue crack is installed on the blade disk.

[0051] The fatigue crack blade 5 is processed by milling the fatigue cracked specimen 1, and the fatigue crack blade 5 includes a blade base 51 and a blade body 52. ​​The fatigue crack 100 is located in the middle of the blade body 52, and a blade fixing hole 53 is processed by drilling on the blade base 51. The fatigue crack blade 5 is installed on the blade disk 6 through the blade fixing hole 53, and the crack-free blades 7 are also evenly installed on the blade disk 6. The number of fatigue crack blades 5 on the blade disk 6 is selected according to the experimental needs, and different numbers of fatigue crack blades 5 are installed at different positions.

[0052] Example 2

[0053] This embodiment is basically the same as Embodiment 1, except that: the measuring system is an industrial video microscope, which detects the length of fatigue cracks in real time based on video, and the crack measurement accuracy reaches 0.3mm, which is suitable for fatigue testing machines without crack extension function.

[0054] In this embodiment, the method for manufacturing a fatigue crack blade includes the following steps:

[0055] S10: Cut out a rectangular parallelepiped sample 1, perform heat treatment on the sample 1, and then prefabricate a notch on one surface of the sample 1 by milling or wire cutting.

[0056] S20: placing the sample 1 on the fixture, installing the fixture on the fatigue testing machine, and installing the industrial video microscope.

[0057] The position of the industrial video microscope and the accuracy of the microscope are adjusted so that the notch 10 of the sample 1 can be clearly observed.

[0058] S30: A three-point bending fatigue test was performed on a fatigue testing machine to pre-form a fatigue crack of 100.

[0059] S40: The industrial video microscope displays the fatigue crack length in real time and determines whether the fatigue crack length reaches a preset fatigue crack length. If the length reaches a preset fatigue crack length, the fatigue testing machine stops running.

[0060] S50: The fatigue testing machine stops running.

[0061] S60: The sample is processed into a blade shape by wire cutting or milling, and during the cutting process, a prefabricated notch 10 is cut off, and a fatigue crack 100 is retained, and the blade containing the fatigue crack is installed on the blade disk.

[0062] The present invention can preform real fatigue cracks by using bending fatigue test. Compared with existing wire cutting notches, fatigue cracks are more consistent with actual cracks produced in engineering. The fatigue crack blade 5 is installed on the blade disk 6, and a rotating crack blade simulation operation test is carried out, which can accurately simulate the crack breathing behavior, which is conducive to studying and analyzing the vibration characteristics of faults caused by actual fatigue cracks, providing an experimental basis for extracting vibration characteristics that are sensitive to crack damage, and effectively developing online diagnostic methods and technologies based on vibration identification of blade fatigue cracks. In addition, the present invention can also use four-point bending fatigue to preform fatigue cracks. The fatigue crack length can be quantitatively preformed by a fatigue testing machine and a COD gauge, and fatigue cracks of different depths can be preformed on the blade. Blade vibration experiments of different fatigue crack depths can be carried out, which can be used to construct a rotating crack blade sample database to provide a data basis for quantitative identification of rotating blade cracks.

[0063] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and the present invention is also intended to include these modifications and modifications.

Claims

1. A method for manufacturing a fatigue crack blade, characterized in that: The following steps are involved: Cut out the specimen, heat treat the specimen first, and then pre-fabricate a notch on one of the surfaces of the specimen by milling or wire cutting; placing a sample on a fixture, installing the fixture on a fatigue testing machine, and installing a measuring system; Fatigue cracks are preformed by performing bending fatigue tests on a fatigue testing machine; The measuring device displays the fatigue crack length in real time and determines whether the fatigue crack length reaches a preset fatigue crack length. When the length reaches a preset fatigue crack length, the fatigue testing machine stops running. The sample is processed into a blade shape by wire cutting or milling, the prefabricated notch is removed during the cutting process, the fatigue crack is retained, and the blade containing the fatigue crack is installed on the blade disk.

2. The method for manufacturing a fatigue crack blade according to claim 1, characterized in that: The notch is a straight-through notch produced by wire cutting, and the radius of curvature at the root of the notch is less than or equal to 0.08 mm.

3. The method for manufacturing a fatigue crack blade according to claim 1, characterized in that: The notch is a milled herringbone notch, and the curvature radius of the notch root is less than or equal to 0.25 mm.

4. The method for manufacturing a fatigue crack blade according to claim 1, characterized in that: By inputting the set crack length on the fatigue testing machine, inputting the stress ratio, maximum loading force, frequency and other parameters, the preset fatigue crack length can be adjusted.

5. The method for manufacturing a fatigue crack blade according to claim 1, characterized in that: A fatigue crack blade is produced by milling a sample containing fatigue cracks, wherein the fatigue crack blade includes a blade base and a blade body, the fatigue crack is located in the middle of the blade body, and a blade fixing hole is produced on the blade base by drilling; the fatigue crack blade is installed on the blade disk through the blade fixing hole, and crack-free blades are also evenly installed on the blade disk; the number of fatigue crack blades on the blade disk is selected according to experimental needs, and different numbers of fatigue crack blades are installed at different positions.

6. A device for manufacturing fatigue crack blades, characterized in that: It comprises a fixture, a fatigue testing machine and a measuring system; the fixture is used to clamp the sample, the fixture is installed on the fatigue testing machine, the fatigue testing machine is used to perform bending fatigue test to preform fatigue cracks; the measuring system is used to measure the length of the fatigue cracks.

7. The device for manufacturing fatigue crack blades according to claim 6, characterized in that: The fixture is a three-point bending fixture, including a single-point support component and a double-point support component, the single-point support component including a first testing machine chuck clamping cylinder, a connecting block, a first side plate and a support pin, one end of the connecting block is fixed on the first testing machine chuck clamping cylinder, the front end of the connecting block is provided with a semi-cylindrical concave surface, both ends of the support pin are fixed to the first side plate by screws, and the support pin shaft body is installed on the semi-cylindrical concave surface; the double-point support component includes a second testing machine chuck clamping cylinder, a supporting platform, a supporting connecting seat, two L-shaped support blocks, a second side plate and a support pin, the support connecting seat is fixed on the second testing machine chuck clamping cylinder, the supporting platform is fixed on the supporting connecting seat, two L-shaped support blocks are arranged relatively on the supporting platform, the front end of the L-shaped support block is provided with a semi-cylindrical concave surface, both ends of the support pin are fixed to the second side plate by screws, and the support pin shaft body is installed on the semi-cylindrical concave surface.

8. The device for manufacturing fatigue crack blades according to claim 6, characterized in that: The fixture is a four-point bending fixture, including two double-point support components, which include a second testing machine chuck clamping cylinder, a support platform, a support connecting seat, two L-shaped support blocks, a second side plate and a support pin. The support connecting seat is fixed on the second testing machine chuck clamping cylinder, the support platform is fixed on the support connecting seat, and two L-shaped support blocks are arranged relatively on the support platform. A semi-cylindrical concave surface is provided at the front end of the L-shaped support block. Both ends of the support pin are fixed to the second side plate by screws, and the support pin shaft is installed on the semi-cylindrical concave surface.

9. The device for manufacturing fatigue crack blades according to claim 6, characterized in that: The measuring system is a COD gauge measuring system, comprising a COD gauge, wherein the COD gauge is used to be clamped on a sample to measure the fatigue crack length on the sample.

10. The device for manufacturing fatigue crack blades according to claim 6, characterized in that: The measuring system is an industrial video microscope, which is installed at an appropriate position to measure fatigue cracks on a sample.

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