Engine blade inherent frequency measuring device

Abstract

The utility model discloses an engine blade inherent frequency measuring device which comprises a rack, a position follow-up collaborative robot, a test support, a sound pressure sensor, an electromagnetic gun, an annular magnetic sensitive sensor, a clamp seat, an air cylinder, a vibration sensor, a quick replacement clamp, a blade radial pressing block and an embedded computer. A position follow-up collaborative robot is fixed to a workbench of the rack and fixedly connected with a testing support, a sound pressure sensor is fixed to one side of the testing support, an electromagnetic gun for emitting magnetic steel balls is fixed to the other opposite side of the testing support, and a clamp base is fixed to the top end of the workbench of the rack. An air cylinder is fixed to the bottom end of the clamp base and drives a blade radial pressing block, rapid replacement clamps are installed on the inner walls of the two opposite sides of the top end of the clamp base, a vibration sensor is fixed to one side of the clamp base, and the outer portion of the steel ball ejection end of the electromagnetic gun is sleeved with an annular magnetic sensitive sensor. The novel blade is convenient to install, high in testing precision and high in working efficiency.

Description

Technical Field

[0001] The utility model relates to the technical field of frequency measuring devices, in particular to a natural frequency measuring device for engine blades. Background Art

[0002] The natural frequency of an engine blade refers to the periodic vibration of the blade at a certain natural frequency under vibration conditions. The frequency of this vibration is the natural frequency of the blade. The natural frequency test of the blade currently mainly includes the beam method, the excitation response method, and the signal analysis method. These methods can be used to obtain the natural frequency and modal shape of the blade and evaluate whether the blade has sufficient stiffness to resist external vibration.

[0003] The previous test method was to place the blade on a positioning fixture that matches the blade before the test, and use a torque wrench to tighten the bolts to press and fix the blade on the fixture to simulate the installation of the blade on the engine rotor disk; use the height quick adjustment mechanism to adjust the position of the electromagnet hitting the blade; use the sound pressure sensor height and angle mounting bracket to adjust the position of the sound pressure sensor. After repeated adjustments and tests, an acceptable position combination is determined, and then the test and analysis of the blades of the same level are started. The test is carried out by energizing the electromagnet to make the armature quickly attract, and the metal knocking head knocks the blade to stimulate the blade to make a sound. It has the following problems:

[0004] 1. The blades are clamped manually, and the clamping and squeezing positions are on both sides of the blades, which is quite different from the actual force conditions of the blades on the engine, affecting the consistency of the measurement results;

[0005] 2. The efficiency of manually pressing the blades is low, and it is difficult to control the size of the pressing force;

[0006] 3. After the electromagnet hits the blade, the rebound is completed by the return spring inside the electromagnet, which has a hysteresis and makes the knocking process longer. In addition, the knocking force is not easy to control, and the sound of the electromagnet rebounding interferes with the test results, especially for the knocking of small blades (the rear stage of the compressor), the test effect is not good;

[0007] 4. When replacing different blades, the installation position of the electromagnet knocking head and the sound pressure sensor that obtains the knocking sound signal needs to be repeatedly adjusted to find a suitable position. Therefore, it requires high personnel requirements, complicated operations, time-consuming and laborious, and affects the efficiency and accuracy of the test;

[0008] 5. The traditional FFT spectrum analysis method regards the signal as a steady-state signal and cannot capture the transient characteristics of the signal. The blade natural frequency test involves a non-steady-state signal and does not consider the transient characteristics of the signal, making it difficult to obtain more accurate spectrum information. Utility Model Content

[0009] The purpose of the present application is to provide a device for measuring the natural frequency of an engine blade to solve the problems raised in the above-mentioned background technology.

[0010] To achieve the above-mentioned purpose, the present application provides the following technical solutions: an engine blade natural frequency measuring device, comprising a frame, a position following collaborative robot, a test bracket, a sound pressure sensor, an electromagnetic gun, an annular magnetic sensitive sensor, a fixture seat, a cylinder, a vibration sensor, a quick-change fixture, a blade radial clamping block and an embedded computer, a position following collaborative robot is fixedly installed on the workbench of the frame, the position following collaborative robot is fixedly connected to the test bracket, a sound pressure sensor is fixedly installed on one side of the test bracket, and a magnetic field sensor is fixedly installed on the other side of the test bracket. An electromagnetic gun for launching magnetic steel balls, a fixture seat is fixedly installed on the top of the workbench of the frame, a cylinder is fixedly installed on the bottom of the fixture seat, the output end of the cylinder is driven and connected to a piston that passes into the fixture seat, the top of the piston is fixedly connected to a blade radial clamping block, quick-change fixtures are installed on the inner walls on both sides of the top of the fixture seat, the quick-change fixtures cooperate with the blade radial clamping block to clamp the blade to be tested, a vibration sensor is fixedly installed on one side of the fixture seat, and an annular magnetic sensitive sensor is fixedly installed on the external sleeve of the steel ball ejection end of the electromagnetic gun.

[0011] Preferably, an embedded computer is fixedly mounted on the frame, and the embedded computer controls the state of the position follower collaborative robot.

[0012] Preferably, the embedded computer input terminal receives the vibration sensor signal and the sound pressure sensor signal, performs joint time-frequency analysis and automatically searches for the natural frequency.

[0013] Preferably, the output end of the embedded computer is electrically connected to a display and a printer, and the display and the printer respectively display and record the natural frequency output by the embedded computer.

[0014] Preferably, the fixture seat and the cylinder are fixed on the frame with screws, the quick-change fixture is adapted to the shape of the tenon at the root of the measured blade, and each set of quick-change fixtures consists of two identical left and right parts, both with positioning dovetail grooves and mounting screw holes.

[0015] In summary, the technical effects and advantages of the utility model are:

[0016] 1. The blade installation is more convenient and more efficient. The size of the pressing force can be accurately controlled by adjusting the cylinder input pressure, and the consistency of the test is guaranteed;

[0017] 2. Using electromagnetic guns to launch steel balls to impact the blades is an ideal way of excitation. The impact intensity can be accurately adjusted by adjusting the energy of the electromagnetic guns.

[0018] 3. The sound pressure sensor and electromagnetic gun position follow-up collaborative robot controls the movement position of the sound pressure sensor and electromagnetic gun, so that the position of the blade, sound pressure sensor and electromagnetic gun is most favorable for the steel ball to hit the blade and obtain the sound signal, which improves the work efficiency, reduces the requirements for operators, and makes the test data more accurate;

[0019] 4. The joint time-frequency analysis method combines the analysis of the time domain and the frequency domain, and can simultaneously analyze the evolution of the signal in time and frequency. The time resolution is improved to a higher level, making the analysis of the transient characteristics of the signal more accurate; the frequency resolution can be adjusted flexibly, which can better adapt to the natural frequency test of blades in different frequency ranges, and broaden the scope of application of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a schematic diagram of the structure of a device for measuring the natural frequency of an engine blade in an embodiment of the present application;

[0022] Figure 2 This is a schematic diagram of the fixture installation structure of an engine blade natural frequency measurement device in an embodiment of the present application;

[0023] Figure 3 This is a structural schematic diagram of a test demonstration of an engine blade natural frequency measurement device in an embodiment of the present application;

[0024] Figure 4 This is a principle block diagram of a device for measuring the natural frequency of an engine blade in an embodiment of the present application;

[0025] Figure 5 This is a cylinder drive block diagram of an engine blade natural frequency measurement device in an embodiment of the present application;

[0026] Figure 6 This is a block diagram of an electromagnetic gun drive device for measuring the natural frequency of an engine blade in an embodiment of the present application.

[0027] In the figure: 1. Frame; 2. Position follow-up collaborative robot; 3. Test bracket; 4. Sound pressure sensor; 5. Electromagnetic gun; 6. Annular magnetic sensitive sensor; 7. Fixture seat; 8. Cylinder; 9. Vibration sensor; 10. Quick change fixture; 11. Blade radial clamping block; 12. Blade; 13. Embedded computer; 14. Display; 15. Printer. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0029] In the description of the present disclosure, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "top", "bottom", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present disclosure. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0030] It should also be noted that the standard parts used in this application document can be purchased from the market, and can be customized according to the description in the specification and drawings. Unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, and it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in this disclosure can be understood according to the specific circumstances, and in the absence of clear limitations, machines, parts and equipment can all adopt conventional models in the prior art.

[0031] In this article, the term "comprising" is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, the elements defined by the sentence "comprising..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0032] Example: Reference Figure 1-6 The engine blade natural frequency measuring device shown in the figure includes a frame 1, a position follower collaborative robot 2, a test bracket 3, a sound pressure sensor 4, an electromagnetic gun 5, an annular magnetic sensitive sensor 6, a fixture seat 7, a cylinder 8, a vibration sensor 9, a quick-change fixture 10, a blade radial clamping block 11 and an embedded computer 12. The position follower collaborative robot 2 is fixedly installed on the workbench of the frame 1, and the position follower collaborative robot 2 is fixedly connected to the test bracket 3. The sound pressure sensor 4 is fixedly installed on one side of the test bracket 3, and a transmitting magnetic sensor is fixedly installed on the other side of the test bracket 3. An electromagnetic gun 5 with a magnetic steel ball, a fixture seat 7 is fixedly installed on the top of the workbench of the frame 1, a cylinder 8 is fixedly installed on the bottom of the fixture seat 7, the output end of the cylinder 8 is driven and connected to a piston inside the fixture seat 7, a blade radial clamping block 11 is fixedly connected to the top of the piston, quick-change fixtures 10 are installed on the inner walls on both sides of the top of the fixture seat 7, the quick-change fixtures 10 cooperate with the blade radial clamping block 11 to clamp the blade to be tested, a vibration sensor 9 is fixedly installed on one side of the fixture seat 7, and an annular magnetic sensitive sensor 6 is fixedly installed on the external sleeve of the steel ball ejection end of the electromagnetic gun 5.

[0033] During the test, the blade to be tested is inserted into the quick-change fixture 10, and the compressed air enters the blade-pressing cylinder 8 through the air filter, the pressure regulator, and the control valve. The cylinder piston moves upward under the action of the air pressure, and the piston pushes the blade radial clamping block 11 from the bottom to the top to press the bottom of the blade 12. The blade is clamped by the precise fit between the root of the blade 12 and the special shape of the fixture. Since the diameter of the piston remains unchanged, the clamping force can be controlled by controlling the pressure of the air source within a certain range.

[0034] The principle of the electromagnetic gun is as follows: the low-voltage direct current is boosted by the boost module and then charged to the high-voltage capacitor to accumulate a large amount of electrical energy. When the transmitting relay is energized, the high-voltage capacitor will instantly discharge through the large-turn coil and generate a strong magnetic field. Under the action of the electromagnetic force, the magnetic steel ball is attracted and flies out of the barrel at high speed by inertia to hit the blades, thereby achieving the excitation of the test.

[0035] With the above structure: an embedded computer 13 is fixedly installed on the frame 1, and the embedded computer 13 controls the state of the position follower collaborative robot.

[0036] By means of the above structure: the input end of the embedded computer 13 receives the signal of the vibration sensor 9 and the signal of the sound pressure sensor 4, and performs joint time-frequency analysis, including short-time Fourier transform (STFT), continuous wavelet transform (CWT), etc., which can simultaneously analyze the evolution of the signal in time and frequency, and automatically search for the natural frequency.

[0037] With the above structure, the output end of the embedded computer is electrically connected to the display 14 and the printer 15, and the display and the printer respectively display and record the natural frequency output by the embedded computer.

[0038] By means of the above structure: the fixture seat, the quick-change fixture, the blade radial clamping block and the cylinder are used to achieve the fixed clamping of the blade. The fixture seat and the cylinder are fixed to the frame with screws, and the blade radial clamping block is installed on the head of the cylinder piston; the quick-change fixture is specially designed according to the different shapes of the tenons at the roots of the blades to be tested. Each group is different, but the positions of the dovetail grooves and six mounting holes of the fixture seat remain unchanged. Each group of quick-change fixtures consists of two identical parts on the left and right, both with positioning dovetail grooves and mounting screw holes. During testing, the selected quick-change fixture is inserted into the fixture seat along the dovetail groove, aligning the holes of the parts and the fixture seat, and then fixed with six screws.

[0039] The working principle of this embodiment is as follows: the blade is fixed by a special fixture that can be quickly replaced and matched with the blade to be tested, and is clamped by radial force of the cylinder to simulate the fixed installation of the blade on the engine; the position follower collaborative robot is controlled by the embedded computer to move the sound pressure sensor and the electromagnetic gun to the predetermined position, so that the position of the blade, the sound pressure sensor and the electromagnetic gun is most favorable for knocking and obtaining sound signals; the exciting device - the electromagnetic gun is energized so that it can launch a magnetic steel ball to hit a certain part of the blade under the action of electromagnetic force and make a sound; the annular magnetic sensitive sensor sends a synchronous signal when the steel ball passes, so that the embedded computer starts to collect the sound pressure sensor installed on the test bracket and the vibration sensor signal on the fixture seat to feel the sound and vibration emitted by the blade vibration, and after acoustic-electric and piezoelectric conversion, signal conditioning and signal collection, the signal is entered into the embedded computer of the device for signal analysis and processing to obtain the blade frequency characteristic signal; the display shows the test results and graphics, and the printer outputs the report.

[0040] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An engine blade natural frequency measuring device, characterized in that: The invention comprises a frame, a position following collaborative robot, a test bracket, a sound pressure sensor, an electromagnetic gun, an annular magnetic sensitive sensor, a fixture seat, a cylinder, a vibration sensor, a quick-change fixture, a blade radial clamping block and an embedded computer. A position following collaborative robot is fixedly installed on the workbench of the frame, the position following collaborative robot is fixedly connected with the test bracket, a sound pressure sensor is fixedly installed on one side of the test bracket, an electromagnetic gun for emitting magnetic steel balls is fixedly installed on the other side of the test bracket, a fixture seat is fixedly installed on the top of the workbench of the frame, a cylinder is fixedly installed on the bottom end of the fixture seat, an output end of the cylinder is driven and connected to a piston passing into the fixture seat, a blade radial clamping block is fixedly connected to the top of the piston, quick-change fixtures are installed on the inner walls on both sides of the top of the fixture seat, the quick-change fixture cooperates with the blade radial clamping block to clamp the blade to be tested, a vibration sensor is fixedly installed on one side of the fixture seat, and an annular magnetic sensitive sensor is fixedly installed on the outer sleeve of the steel ball ejection end of the electromagnetic gun.

2. The engine blade natural frequency measuring device according to claim 1, characterized in that: An embedded computer is fixedly mounted on the frame, and the embedded computer controls the state of the position follower collaborative robot.

3. The engine blade natural frequency measuring device according to claim 2, characterized in that: The input end of the embedded computer receives the vibration sensor signal and the sound pressure sensor signal, performs joint time-frequency analysis and automatically searches for the natural frequency.

4. The engine blade natural frequency measuring device according to claim 2, characterized in that: The output end of the embedded computer is electrically connected to a display and a printer, and the display and the printer respectively display and record the natural frequency output by the embedded computer.

5. The engine blade natural frequency measuring device according to claim 1, characterized in that: The fixture seat and the cylinder are fixed on the frame with screws. The quick-change fixture is adapted to the shape of the tenon at the root of the blade to be measured. Each set of quick-change fixtures consists of two identical left and right parts, both with positioning dovetail grooves and mounting screw holes.

Images