A clamp and test method for fatigue vibration test of multi-type blades

Abstract

The application discloses a kind of clamps and test methods for multiple types of blade fatigue vibration test.The clamp includes base, chuck, first module and second module;Chuck is ladder-shaped structure, and its horizontal ladder part is provided with sliding groove;First module is fixed to chuck by right-angle L-shaped matching surface;Second module includes sliding base matched with sliding groove and clamping main body oppositely arranged with first module, which enclose clamping area adapted to blade tenon;There are also horizontal and vertical two-way locking mechanisms to ensure stable clamping.The method realizes overall surface contact between blade tenon and clamp through module selection, parallel sliding clamping and two-way locking steps.The application solves the problems of traditional C-shaped clamp, such as line contact, uneven stress, single application range, etc., and has the advantages of stable clamping, wide applicability, high test consistency, etc., and is particularly suitable for fatigue vibration test of various blades of aero-engine.

Description

Technical Field

[0001] This invention relates to the field of physical and chemical testing technology, specifically to a fixture and testing method that can be used for fatigue vibration testing of various types of blades. Background Technology

[0002] Blades are among the most critical components of aero-engines, operating at high temperatures, under complex stress conditions, and in harsh environments, demanding extremely high performance. To evaluate blade performance, rotating blades undergo batch sampling and vibration fatigue testing to verify the rationality of the materials and manufacturing processes used in that batch, and to assess whether the blades' fatigue performance meets requirements. Fatigue vibration testing of blades requires the use of fixtures to hold their tenons. Rotating blades come in many types, including fan blades, rotor blades, and turbine blades. The tenon profiles of different types of blades vary, with common examples including dovetail tenons and fir tree tenons. Blades of the same type may have similar profiles, but their dimensions differ. Even blades with the same part number may have slight differences in tenon dimensions due to manufacturing tolerances.

[0003] Traditional clamps are generally C-shaped clamps, see Figure 1 As indicated by the arrow, pressure is applied to the fixture. Ideally, the distance between areas B and C decreases in parallel, forming surface contact with the blade's meshing surface and clamping the blade. However, in practice, when pressure is applied to areas B or C, area A constrains the deformation area, causing the distance between B and C to decrease in an approximately "V" shape rather than in parallel. This results in an approximately line contact between the meshing surface and the fixture. This type of contact is unstable, and uneven local contact may lead to blade instability during the test, resulting in a low fault tolerance rate. This type of traditional fixture is only suitable for blades of the same part number, limiting its applicability. Furthermore, blades of the same part number have different tenon dimensions due to machining tolerances. While the fixture dimensions are fixed, the difference in tenon dimensions leads to inconsistent C-clamp opening widths when clamping the blade tenons. This inevitably results in inconsistent stress points during vibration testing, leading to poor consistency and stability in fatigue assessment tests.

[0004] To address the aforementioned issues, several improvements have been proposed in existing technologies. For example, Chinese utility model patent CN219254811U discloses a machining and fixing fixture for aero-engine blade production. This fixture achieves rapid blade clamping and improves clamping efficiency by using a sliding groove, an L-shaped connecting block, and an electric push rod to drive the clamping block. Another Chinese utility model patent CN215554266U provides a tooling fixture for compressor rotor blades. It uses a first clamping seat and a second clamping seat to form a clamping cavity, and utilizes a locking assembly with pads to clamp the blade tenons, aiming to improve clamping stability and repeatability.

[0005] However, the aforementioned existing improvement solutions still have certain limitations. The former mainly focuses on improving the clamping efficiency of blades of a single specification, and does not offer a systematic solution for the adaptability of tenons of multiple types and sizes of blades; while the latter improves the stability of specific structures (such as dovetail tenons), its versatility is insufficient and it is difficult to cover the clamping requirements of tenons with different contour shapes. Therefore, developing a blade fatigue vibration test fixture that can adapt to multiple tenon types and sizes, provide stable and reliable clamping, and has good fault tolerance has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to develop a clamp and its usage method for fatigue vibration testing of rotating blades. This clamp can be used for various types of blades and ensures that the clamping surfaces are in surface contact when clamping different blades, resulting in uniform force, stable and tight clamping force, and thus ensuring the consistency and stability of the vibration fatigue test.

[0007] The technical solution of the present invention: a fixture that can be used for fatigue vibration testing of multiple types of blades, including a base, a stepped clamp inclined on the base, a first module fixed on the clamp, and a slidable second module. The clamp is an L-shaped stepped structure, and a sliding groove is provided inside the side wall of its horizontal stepped part. The first module is fixedly mounted on the upper end face of the horizontal step of the clamp; The second module includes a sliding base and a clamping body. The sliding base is slidably fitted into the groove of the chuck, and the clamping body is disposed on the upper end surface of the horizontal step of the chuck and is arranged opposite to the first module to jointly form a clamping area for clamping the blade.

[0008] Furthermore, the first module is a trapezoidal body with a parallel upper base and a lower base. The upper base and the lower base are rectangles with similar shapes but different areas, and the area of ​​the lower base is smaller than that of the upper base. The trapezoidal body also includes two trapezoidal side surfaces and two rectangular side surfaces, and the two rectangular side surfaces are a vertical side surface and an inclined side surface, respectively.

[0009] Furthermore, the first module contacts the upper surface and side wall of the horizontal step of the clamp through its bottom surface and vertical side surface, respectively, forming a right-angled "L"-shaped mating interface.

[0010] Furthermore, the sliding base of the second module (4) is a rectangular block, which is integrally connected to the clamping body with the same structure as the first module through a connecting part. The inclined side of the clamping body is set opposite to the inclined side of the first module, thereby forming a clamping area.

[0011] Furthermore, the sliding base is slidably disposed in the groove of the chuck, and a threaded hole is provided on the sliding base along the horizontal direction. A bolt is provided to pass through the threaded hole and extend to the other side of the chuck, and the position is locked by cooperating with the nut and washer.

[0012] Furthermore, the groove is provided with a lubricating medium for lubricating the sliding pair.

[0013] Furthermore, both the first module and the second module have vertically threaded holes on their clamping bodies, and are fastened to the upper end face of the horizontal step of the clamp by bolts.

[0014] Furthermore, the upper end of the horizontal step of the chuck is provided with an oblong hole corresponding to the fixed position of the clamping body of the second module, which is used to cooperate with the vertical threaded hole at the beginning of the second module to fix and adjust the position of the second module.

[0015] Furthermore, the base is a flange base.

[0016] A test method includes the following steps: Step 1: Fixture installation. Secure the fixture to the vibration test bench via the mounting part of its base. Step 2: Module selection and installation. Select and install the first module and the second module according to the blade tenon profile. The first module is fixed to the chuck, and the second module is inserted into the groove of the chuck through its sliding base. Step 3: Blade clamping. Place the blade tenon in the clamping area formed by the first module and the second module, slide the second module to make it fit tightly against one side of the tenon, while the first module fits against the other side of the tenon. Step 4: Bidirectional locking. Operate the horizontal bolts in sequence to fix the position of the second module in the X-axis direction, and operate the vertical bolts to suppress the warping of the second module in the Z-axis direction, thereby completing the bidirectional constraint of the blade tenon. Step 5: Test execution. Start the vibration test bench and conduct fatigue vibration tests on the blades.

[0017] The beneficial effects of this invention are: 1) The fixture of the present invention uses sliding contact and sliding clamping process. The contour surfaces on both sides of the blade tenon are parallel to the clamping surfaces corresponding to the first and second modules of the fixture, ensuring that the tenon and the fixture are in surface contact during clamping. Even if there are machining tolerances, the contact surface can be kept unchanged and the force points can be consistent by adjusting the fastening bolts, so as to ensure the stability and consistency of the test.

[0018] 2) In addition to the fastening bolts in the X-axis direction applying fastening force, the protruding rectangular slider of the second module and the sliding groove of the clamp body play an auxiliary positioning role in the clamp of the present invention, ensuring that the second module does not shift; the fastening bolts in the Z-axis direction also apply fastening force, and the blade tenon is subjected to fastening force in two directions, making the clamping more stable.

[0019] 3) This invention can clamp various types of blades by replacing the first module and the second module, and has a wide range of applications. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the stress analysis of a traditional C-shaped clamp structure and clamping tenon; Figure 2 This is a schematic diagram of the overall structure of the fixture of the present invention; Figure 3 This is an exploded view of the chuck of the present invention; Figure 4 This is a schematic diagram of the clamp fitting of the present invention; Reference numerals: 1-base; 2-clamp; 3-first module; 4-second module; 41-base; 42-clamping body. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should not be construed that the scope of the subject matter of the present invention is limited to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0023] Fixture Design: The overall structure of the fixture consists of two parts: one is the chuck 2 that holds the blades, and the other is the base 1 flange that connects to the vibration table. See [link / details]. Figure 2 .

[0024] See chuck design Figure 3 The chuck body and the base flange are integrated into one piece. Figure 2 Red, Module 3 of the first module. Figure 2 Green, Module 4 is Figure 2The blue components are used to clamp the blade. The combined profile of the first module 3 and the second module 4 matches the profile of the tenon of the clamped blade. The contact surface between the first module 3 and the main body is a right-angled "L" shape, and it is fixed to the main body using a fastening bolt through the #1 threaded hole. The reaction force of clamping the blade tenon is mainly offset by the stress generated by the contact surface between the first module 3 and the main body, and the bolt in the #1 threaded hole mainly serves the function of fastening.

[0025] The main rectangular slide groove matches the dimensions of the protruding rectangular sliding base 41 of the second module 4, allowing them to slide together. A tight fit is required, and lubricant can be used to assist in the sliding motion. This tight fit serves a positioning function, preventing the second module 4 from shifting position during vibration fatigue testing. See [link to relevant documentation]. Figure 4 When the second module 4 and the first module 3 are engaged with the blade tenon, the bolt passes through the #3 threaded hole, through the second module 4 and the clamp 2, and is tightened on the other side using a fastening nut and washer. Unlike the traditional "C" shaped clamp, due to the parallel sliding clamping, the engagement method between the first module 3 and the second module 4 and the blade tenon is surface contact.

[0026] The #2 thread mates with the oblong hole, the semicircular diameter of which matches the diameter of the #2 threaded hole; the oblong hole passes through the chuck. A fastening bolt is passed through the #2 threaded hole and the #2 groove, and then a nut and washer are used for reinforcement at the bottom of the chuck body. This bolt tightening prevents the second module 4 from tilting in the Z direction under excessive force in the X direction, ensuring that the first module 3 and the second module 4 are always in surface contact with the tenon; secondly, it provides auxiliary reinforcement in the X-axis direction.

[0027] For blades of the same part number, even with machining tolerances, the contact between the blade and the tenon remains surface-to-surface as long as the tenon profile remains unchanged. This ensures consistent stress points during vibration and guarantees the consistency and stability of the test. For blades of different part numbers, the first module 3 and the second module 4 are replaced with matching modules according to the blade's tenon profile.

[0028] Example 1: This example provides a fixture that can be used for fatigue vibration testing of various types of blades, and its structure is as follows. Figures 2 to 4 As shown, it mainly includes a base 1, a clamp 2, a first module 3, and a second module 4.

[0029] The base 1 is equipped with a flange, which is used to fix the entire fixture to the vibration test bench by tightening bolts, so as to ensure the stability of the fixture during the test.

[0030] The chuck 2 has a stepped structure, which provides excellent structural rigidity. The horizontal stepped part of the chuck 2 has a sliding groove inside its side wall. The size of the sliding groove is precisely matched with the sliding base 41 of the second module 4 to form a sliding pair.

[0031] The first module 3 has a trapezoidal structure. Its bottom surface and vertical side surface form a right-angled L-shaped mating surface with the chuck 2. It is then fixed to the upper end of the horizontal step of the chuck 2 using a fastening bolt through the #1 threaded hole. The inclined side of the first module 3 perfectly matches the contour of one side of the tenon of the blade to be clamped.

[0032] The second module 4 includes a sliding base 41 and a clamping body 42. The sliding base 41 is a rectangular block that can slide smoothly along the groove 21 of the clamp 2. The clamping body 42 is integrally connected to the sliding base 41 via a journal, and its structure corresponds to that of the first module 3, having an inclined side that matches the contour of the other side of the blade tenon.

[0033] The second module 4 is equipped with a horizontal locking mechanism, including a #3 threaded hole and a corresponding locking bolt. When the second module 4 slides to the predetermined position, the locking bolt can be tightened to fix the position of the second module 4 in the X-axis direction.

[0034] The chuck 2 is also equipped with a vertical locking mechanism, including a #2 oblong hole and a corresponding fastening bolt. The bolt passes through the oblong hole and the corresponding hole of the second module 4, and is fastened at the bottom of the chuck 2 by a nut. This not only prevents the second module 4 from tilting in the Z-axis direction, but also provides auxiliary positioning in the X-axis direction.

[0035] This embodiment achieves parallel clamping through the relative sliding of the first module 3 and the second module 4, ensuring simultaneous surface contact on both sides of the blade tenon, thus solving the line contact problem caused by deformation constraints in traditional C-shaped clamps. The bidirectional locking mechanism applies clamping force simultaneously in the X and Z axes, significantly improving clamping stability and preventing loosening or displacement during testing. The modular design gives the clamp excellent adaptability; by replacing the first module 3 and the second module 4 with different profiles, it can accommodate various types of blade tenons, greatly expanding its application range. For blades of the same type but with machining tolerances, adjusting the locking mechanism still ensures surface contact, guaranteeing the consistency and comparability of the tests.

[0036] Example 2: This example provides a blade fatigue vibration test method using the above-mentioned fixture. This method effectively solves the problems mentioned in the background art, such as uneven contact, inconsistent force points, and limited applicability of traditional fixtures.

[0037] The experimental method includes the following steps: Step 1: Secure the fixture to the vibration test bench using the flange of base 1, ensuring a firm and reliable installation.

[0038] Step 2: Based on the contour features of the tenon of the blade to be tested, select the first module 3 and the second module 4 with corresponding profiles, and fix the first module 3 to the chuck 2 through the #1 threaded hole.

[0039] Step 3: Apply an appropriate amount of lubricating oil to the sliding base 41 of the second module 4, insert it into the sliding groove 21 of the chuck 2, and slide it along the groove to the appropriate position.

[0040] Step 4: Place the blade tenon in the clamping area formed by the first module 3 and the second module 4, push the second module 4 so that its clamping body 42 fits tightly against one side of the blade tenon, while the first module 3 fits against the other side of the tenon, forming a stable surface contact state.

[0041] Step 5: Secure the blade tenon in the X-axis direction using the horizontal locking mechanism, and tighten the locking bolts of the #3 threaded hole in sequence to ensure that the clamping force is evenly distributed.

[0042] Step 6: Secure the blade tenon in the Z-axis direction using the vertical locking mechanism. Use a fastening bolt to pass through the #2 waist-shaped hole and the corresponding hole of the second module 4, and lock it with a nut at the bottom of the chuck 2 to prevent the second module 4 from tilting up during the test.

[0043] Step 7: After confirming that all locking mechanisms are securely fastened, start the vibration test bench and conduct a blade fatigue vibration test.

[0044] This embodiment uses a parallel sliding clamping method to ensure that the blade tenon and the clamp always maintain surface contact, effectively avoiding the line contact problem of traditional clamps and improving the accuracy and reliability of the test. Its bidirectional locking mechanism subjectes the blade to multidirectional constraints during vibration testing, significantly enhancing clamping stability and preventing loosening and displacement during the test.

[0045] The method provided in this embodiment achieves the standardization and normalization of blade fatigue vibration testing, providing reliable technical support for the performance evaluation of aero-engine blades.

[0046] The foregoing has provided a detailed description of a fixture and testing method for fatigue vibration testing of various types of blades provided by the present invention. Specific examples have been used to illustrate the structure and working principle of the invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A fixture that can be used for fatigue vibration testing of various types of blades, characterized in that: It includes a base (1), a stepped chuck (2) inclined on it, a first module (3) fixed on the chuck (2), and a slidable second module (4). The chuck (2) is an L-shaped stepped structure, and a groove is provided inside the side wall of its horizontal stepped part. The first module (3) is fixedly set on the upper end face of the horizontal step of the clamp (2). The first module (3) is a trapezoidal body with a parallel upper base and a lower base. The upper base and the lower base are rectangles with similar shapes but different areas, and the area of ​​the lower base is smaller than that of the upper base. The trapezoidal body also includes two trapezoidal sides and two rectangular sides. The two rectangular sides are a vertical side and an inclined side, respectively. The first module (3) contacts the upper end face and the side wall of the horizontal step of the clamp (2) through its lower base and vertical side, respectively, and together form a right-angled "L" shaped mating interface. The second module (4) includes a sliding base (41) and a clamping body (42). The sliding base (41) is slidably fitted into the groove of the chuck (2). The clamping body (42) is disposed on the upper end face of the horizontal step of the chuck (2) and is arranged opposite to the first module (3) to jointly form a clamping area for clamping blades. Both the clamping bodies (42) of the first module (3) and the second module (4) have vertical threaded holes and are fastened to the upper surface of the horizontal step of the clamp (2) by bolts. The upper end of the horizontal step of the clamp (2) is provided with a waist-shaped hole at the fixed position of the clamping body (42) of the second module (4), which is used to cooperate with the vertical threaded hole of the second module (4) to fix and adjust the position of the second module (4).

2. The fixture for fatigue vibration testing of multiple types of blades according to claim 1, characterized in that: The sliding base (41) of the second module (4) is a rectangular block. The rectangular block is integrally connected to the clamping body (42) with the same structure as the first module (3) through a connecting part. The inclined side of the clamping body (42) is set opposite to the inclined side of the first module (3) to form a clamping area.

3. The fixture for fatigue vibration testing of multiple types of blades according to claim 2, characterized in that: The sliding base (41) is slidably disposed in the groove of the chuck (2). The sliding base (41) has a threaded hole along the horizontal direction. A bolt passes through the threaded hole and extends to the other side of the chuck (2). The position is locked by cooperating with the nut and washer.

4. The fixture for fatigue vibration testing of multiple types of blades according to claim 1, characterized in that: The groove is provided with a lubricating medium for lubricating the sliding pair.

5. The fixture for fatigue vibration testing of multiple types of blades according to claim 1, characterized in that: The base (1) is a flange base.

6. A testing method using the fixture according to any one of claims 1-5, characterized in that: Includes the following steps, Step 1: Fixture installation, fix the fixture to the vibration test bench through the mounting part of its base (1); Step 2: Module selection and installation. Select and install the first module (3) and the second module (4) according to the blade tenon profile. The first module (3) is fixed on the chuck (2), and the second module (4) is inserted into the groove of the chuck (2) through its sliding base (41). Step 3: Blade clamping. Place the blade tenon in the clamping area formed by the first module (3) and the second module (4), slide the second module (4) to make it fit tightly against one side of the tenon, while the first module (3) fits against the other side of the tenon. Step 4: Bidirectional locking. Operate the horizontal bolts in sequence to fix the position of the second module (4) in the X-axis direction, and operate the vertical bolts to suppress the warping of the second module (4) in the Z-axis direction, thereby completing the bidirectional constraint of the blade tenon. Step 5: Test execution. Start the vibration test bench and conduct fatigue vibration tests on the blades.

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