Milling cutter blade defect detection device and defect detection method

Abstract

The invention relates to the field of nondestructive testing, in particular to a milling cutter blade defect detection device and method. The method comprises the following steps of: firstly, calculating and drawing a wedge-shaped guided wave propagation group velocity frequency dispersion curve by establishing a milling cutter blade fluctuation mechanical model and adopting a double-Laguerre polynomial series analytical solution method; the optimal excitation frequency for milling cutter blade quality detection is selected according to the group velocity frequency dispersion curve, and implementation of wedge-shaped guided wave quality detection can be efficiently guided. The wedge-shaped guided wave quality detection device of the milling cutter blade is established, noise reduction processing and weak signal extraction are carried out on wedge-shaped guided wave signals obtained through detection, and rapid, convenient and comprehensive health condition detection on the milling cutter blade is facilitated. According to the detection method and device, the optimal excitation frequency of wedge-shaped guided wave quality detection can be efficiently found through a theoretical method, comprehensive quality detection can be conducted on milling cutter blade structures of different specifications through the wedge-shaped milling cutter fixing device, and the signal-to-noise ratio and reliability of quality detection of the milling cutter blade structures are improved.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing, and in particular to a device and method for detecting defects in milling cutter cutting edges. Background Technology

[0002] In modern industrial technology, end mills, with their advantages of high-strength alloy matrix, modular geometry and multi-layer composite coating, have played a vital role in high-end manufacturing fields such as aerospace, precision molds and automotive powertrains.

[0003] However, under extreme conditions of high-speed cutting and intermittent cutting, the tool surface will be subjected to extremely strong contact stress. During its service life, the milling cutter edge will inevitably develop structural defects, such as cracks and voids, as well as plastic deformation of the cutting edge caused by thermomechanical fatigue. These defects will not only cause an increase in the fluctuation of cutting force, directly causing the workpiece surface waviness to exceed the standard, but may even lead to sudden chipping of the tool.

[0004] Currently, the most widely used method for milling cutter inspection in the industry is the digital microscope inspection system, which observes the wear degree of the milling cutter through microscopic optical magnification. However, it has significant limitations in the detection of three-dimensional structural defects, and suffers from low detection accuracy and low detection efficiency. Summary of the Invention

[0005] In view of the shortcomings of existing technologies in the quality inspection of in-service milling cutter cutting edges, the present invention aims to provide a milling cutter cutting edge defect detection device and defect detection method to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows: A milling cutter cutting edge defect detection device, comprising: A worktable is provided with a mounting base for a milling cutter to be tested, and the milling cutter to be tested is detachably mounted on the mounting base; the mounting base is horizontally rotatable on the worktable. A robotic arm, one end of which is mounted on the worktable and the robotic arm is spaced apart from the mounting base; An ultrasonic transducer is mounted on the free end of the robotic arm, and the robotic arm is adapted to drive the ultrasonic transducer to move so that it is directly opposite the cutting edge of the milling cutter to be tested. A guided wave detector is mounted on the workbench and electrically connected to the ultrasonic transducer. The guided wave detector is used to excite and receive signals of a preset frequency.

[0007] Preferably, the worktable includes: Support legs, wherein multiple support legs are provided, and the multiple support legs are arranged parallel to each other and spaced apart along the circumferential direction of the worktable; A top plate is connected to the top of the support leg. The top plate has a through hole, and the central axis of the through hole is perpendicular to the top plate. The robotic arm and the waveguide detector are mounted on the top plate. A base plate and a top plate are arranged parallel to each other and spaced apart. The base plate is connected to the support leg. The ends of the base plate and the support leg that are away from the top plate are spaced apart. The base plate, the top plate and the support leg together define a mounting cavity, and the through hole communicates with the mounting cavity. A rotating platform, a portion of which is disposed within the mounting cavity, wherein the central axis of the rotating platform coincides with the central axis of the through hole, and one end of the rotating platform facing away from the base plate is located on the upper side of the top plate; a mounting base is fixedly disposed on the rotating platform, and the central axis of the mounting base coincides with the central axis of the through hole. A drive mechanism is provided inside the mounting cavity, the drive mechanism is connected to the rotating platform, and the drive mechanism is adapted to drive the rotating platform to rotate.

[0008] Preferably, the drive mechanism includes: A first drive motor is disposed in the mounting cavity, and the first drive motor and the through hole are spaced apart in the length direction of the top plate. A transmission disk is rotatably disposed within the mounting cavity, and the central axis of the transmission disk coincides with the central axis of the through hole. The first driving mechanism drives the transmission disk to rotate via a transmission belt, and the rotating platform is fixed on the transmission disk.

[0009] Preferably, the mounting base is provided with a first slide rail and a second slide rail located on the same straight line, and the milling cutter edge defect detection device further includes: The first claw has one end movably engaged in the first slide rail, and the other end of the first claw forms a first clamp. The second claw has one end movably engaged in the second slide rail, and the other end of the second claw forms a second clamp; A second drive motor is mounted on the mounting base and located at the opposite ends of the first and second slide rails. The central axis of the second drive motor coincides with the central axis of the mounting base. The second drive motor is adapted to drive the first jaw to move along the first slide rail and drive the second jaw to move along the second slide rail, so that the first jaw and the second jaw switch between a first state and a second state; in the first state, the first clamp and the second clamp are separated, and the milling cutter to be tested is adapted to be clamped on the separated first clamp and the second clamp; in the second state, the first clamp and the second clamp are close together, and the milling cutter to be tested is adapted to be removed from the first clamp and the second clamp.

[0010] Preferably, the milling cutter cutting edge defect detection device further includes: A rotating arm is fixedly mounted on the output shaft of the second drive motor, and the center of the rotating arm coincides with the output shaft of the second drive motor. A first pivot arm, one end of which is pivotally connected to the first chuck, and the other end of which is pivotally connected to one end of the rotating arm; A second pivot arm, one end of which is pivotally connected to the second chuck, and the other end of which is pivotally connected to the other end of the rotating arm. When the second drive motor rotates forward, it is adapted to drive the first jaw and the second jaw to move in a direction away from each other, so as to separate the first clamp and the second clamp. When the second drive motor reverses, it is adapted to drive the first and second jaws to move toward each other, so that the first and second clamps are brought closer together.

[0011] Preferably, the robotic arm includes: The fixed base is connected and fixed to the worktable; A first connecting arm, one end of which is rotatably connected to the top of the fixed base via a first motor; The second connecting arm, one end of which is rotatably connected to the other end of the first connecting arm via a second motor; A snap-fit ​​connector is rotatably connected to the other end of the second connecting arm via a third motor, and the ultrasonic transducer is adapted to be snapped onto the snap-fit ​​connector.

[0012] A defect detection method based on the above-mentioned milling cutter cutting edge defect detection device, the defect detection method comprising: S1: Based on the three-dimensional linear elasticity theory, a wave dynamics model with the same material and wedge angle as the cutting edge structure of the milling cutter under test is established. The double Laguerre polynomial series analytical solution method is used to obtain the group velocity dispersion curve of the wedge-shaped guided wave propagation in the wave dynamics model. S2: Perform mode differentiation on the acquired group velocity dispersion curve, and select the maximum group velocity value of a specific mode. The optimal excitation frequency for detection by the guided wave detector; S3: Fix the milling cutter to be tested on the mounting base, start the milling cutter edge defect detection device, obtain the echo signal detected by the guided wave detector, and calculate the defect reflection echo time difference Δt; S4: Based on the time difference Δt of the defect reflection echo and the group velocity value of the wedge-shaped guided wave propagation. Calculate and determine the location of structural defects in the milling cutter's cutting edge.

[0013] Preferably, the calculation of the defect reflection echo time difference Δt includes: S31: Perform wavelet transform processing on the time-domain signal of the echo signal detected by the guided wave detector to obtain wavelet coefficients for multiple frequency bands; S32: Select one or more frequency bands for wavelet coefficient reconstruction to obtain a reconstructed signal; S33: After denoising the primary reconstructed signal and enhancing the weak signal features, a secondary reconstructed signal is obtained. The times corresponding to the maximum amplitude values ​​of the excitation signal and the defect reflection echo signal in the secondary reconstructed signal are t and t, respectively. d And t, that is, tt d The time difference Δt is the defect reflection echo from the milling cutter cutting edge.

[0014] Preferably, in step S4, the distance L between the defect location and the excitation end face of the milling cutter is calculated using the following formula: .

[0015] Compared with the prior art, the beneficial effects of the present invention are: The milling cutter edge defect detection device described in this invention uses a mounting base to fix the milling cutter under test. When detecting the next milling cutter edge, there is no need to disassemble and reassemble the milling cutter. Instead, the mounting base controls the rotation of the milling cutter, and a robotic arm controls the ultrasonic transducer to detach from the previous milling cutter edge and abut against the next milling cutter edge. Due to the rotation angle and the fixed movement of the robotic arm, the force and position of the ultrasonic transducer, after being bonded to the end face of the milling cutter edge with a coupling agent are the same, eliminating errors caused by differences in excitation position and bonding force. This not only improves the accuracy of milling cutter edge health detection and assessment but also avoids damage to the milling cutter edge, making it convenient, quick, and suitable for batch health detection of milling cutter edges.

[0016] The present invention provides a method for detecting defects in milling cutter edges based on wedge-guided waves. By establishing a dynamic model of the milling cutter edge wave and employing a double Laguerre polynomial series analytical solution method, the dispersion curve of the wedge-guided wave propagation is calculated and plotted. Based on the group velocity dispersion curve, the optimal excitation frequency for milling cutter edge quality detection is selected, and then an ultrasonic transducer corresponding to the optimal excitation frequency is quickly selected, which can efficiently guide the implementation of wedge-guided wave quality detection.

[0017] This invention uses wavelet transform to obtain local time-frequency features, and selects one or more frequency band wavelet coefficients for reconstruction through inverse wavelet transform to achieve noise reduction of guided wave signals and enhancement extraction of weak signals, thereby obtaining the time difference of reflected echoes from blade structure defects, which can more accurately assess the health status of the blade structure. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the milling cutter edge defect detection device of the present invention; Figure 2 The group velocity dispersion curve of the wedge-shaped guided wave propagation according to the present invention; Figure 3 This is a schematic diagram of the worktable structure of the milling cutter edge defect detection device of the present invention; Figure 4 This is a schematic diagram of the rotating platform and mounting base structure of the milling cutter edge defect detection device of the present invention; Figure 5 This is a schematic diagram of the robotic arm structure of the milling cutter edge defect detection device of the present invention; Figure 6 This is a schematic diagram of the propagation of the wedge-shaped guided wave of the present invention within a defective milling cutter edge; Figure 7 This is a schematic diagram of the wedge-shaped waveguide detection method of the present invention; Figure 8 This is a schematic diagram of the wedge-shaped guided wave detection after noise reduction processing according to the present invention; Figure 9 This is a schematic diagram of the wedge-shaped guided wave detection after weak signal enhancement according to the present invention; The labels in the attached diagram are as follows: 1-Workbench; 2-Robotic arm; 3-Ultrasonic transducer; 4-Guided wave detector; 1.1-Support leg; 1.2-Drive mechanism; 1.3-Rotating platform; 1.4-Top plate; 1.5-Bottom plate; 1.6-Mounting cavity; 1.7-Through hole; 1.8-Mounting base; 1.2.1-First drive motor; 1.2.2-Belt; 1.2.3-Transmission disc; 1.8.1-First slide rail; 1.8.2-Rotating arm; 1 1.8.3 - First gripper; 1.8.4 - First pivot arm; 1.8.5 - First clamp; 1.8.6 - Second clamp; 1.8.7 - Second pivot arm; 1.8.8 - Second gripper; 1.8.9 - Second drive motor; 1.8.10 - Second slide rail; 2.1 - Fixed base; 2.2 - First motor; 2.3 - First connecting arm; 2.4 - Second motor; 2.5 - Second connecting arm; 2.6 - Third motor; 2.7 - Clamping component. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0020] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", etc., which indicate the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0021] A milling cutter cutting edge defect detection device, comprising: The worktable 1 is provided with a mounting base 1.8 for a milling cutter to be tested, and the milling cutter to be tested is detachably mounted on the mounting base 1.8; the mounting base 1.8 is horizontally rotatable on the worktable 1. Robotic arm 2, one end of which is mounted on the worktable 1, and the robotic arm 2 is spaced apart from the mounting base 1.8; An ultrasonic transducer 3 is mounted on the free end of the robotic arm 2. The robotic arm 2 assembly is adapted to drive the ultrasonic transducer 3 to move so that it is directly opposite the cutting edge of the milling cutter to be tested. A guided wave detector 4 is mounted on the workbench 1 and is electrically connected to the ultrasonic transducer 3. The guided wave detector 4 is used to excite and receive signals of a preset frequency.

[0022] The workbench 1 includes: Support legs 1.1, wherein multiple support legs 1.1 are provided, and the multiple support legs 1.1 are arranged parallel to each other and spaced apart along the circumferential direction of the worktable 1; Top plate 1.4 is connected to the top of the support leg 1.1. The top plate 1.4 has a through hole 1.7. The central axis of the through hole 1.7 is perpendicular to the top plate 1.4. The robotic arm 2 and the waveguide detector 4 are mounted on the top plate 1.4. A base plate 1.5 is provided, and the base plate 1.5 and the top plate 1.4 are arranged in parallel and spaced apart. The base plate 1.5 is connected to the support leg 1.1. The ends of the base plate 1.5 and the support leg 1.1 that are away from the top plate 1.4 are spaced apart. The base plate 1.5, the top plate 1.4 and the support leg 1.1 together define a mounting cavity 1.6, and the through hole 1.7 communicates with the mounting cavity 1.6. A rotating platform 1.3 is partially disposed within the mounting cavity 1.6. The central axis of the rotating platform 1.3 coincides with the central axis of the through hole 1.7, and the end of the rotating platform 1.3 facing away from the base plate 1.5 is located on the upper side of the top plate 1.4. The mounting base 1.8 is fixedly disposed on the rotating platform 1.3, and the central axis of the mounting base 1.8 coincides with the central axis of the through hole 1.7. A drive mechanism 1.2 is disposed within the mounting cavity 1.6. The drive mechanism 1.2 is connected to the rotating platform 1.3 and is adapted to drive the rotating platform 1.3 to rotate.

[0023] The drive mechanism 1.2 includes: The first drive motor 1.2.1 is disposed in the mounting cavity 1.6, and the first drive motor 1.2.1 and the through hole 1.7 are spaced apart in the length direction of the top plate 1.4. The transmission disk 1.2.3 is rotatably disposed within the mounting cavity 1.6, and the central axis of the transmission disk 1.2.3 coincides with the central axis of the through hole 1.7. The first driving mechanism 1.2 drives the transmission disk 1.2.3 to rotate via the transmission belt 1.2.2, and is used to drive the milling cutter to rotate when the milling cutter detects the next cutting edge to be tested. The rotating platform 1.3 is fixed on the transmission disk 1.2.3.

[0024] The mounting base 1.8 is provided with a first slide rail 1.8.1 and a second slide rail 1.8.10 located on the same straight line. The milling cutter edge defect detection device further includes: The first claw 1.8.3 has one end movably engaged in the first slide rail 1.8.1, and the other end of the first claw 1.8.3 forms a first clamp 1.8.5; The second claw 1.8.8 has one end movably engaged in the second slide rail 1.8.10, and the other end of the second claw 1.8.8 forms a second clamp 1.8.6; A second drive motor 1.8.9 is mounted on the mounting base 1.8, and is located at the ends of the first slide rail 1.8.1 and the second slide rail 1.8.10 facing each other. The central axis of the second drive motor 1.8.9 coincides with the central axis of the mounting base 1.8. The second drive motor 1.8.9 is adapted to drive the first jaw 1.8.3 to move along the first slide rail 1.8.1 and drive the second jaw 1.8.8 to move along the second slide rail 1.8.10, so that the first jaw 1.8.3 and the second jaw 1.8.8 switch between a first state and a second state, facilitating the disassembly and installation of the end mill under test on the first clamp 1.8.5 and the second clamp 1.8.6 of the mounting base 1.8; specifically, in the first state, the first clamp 1.8.5 and the second clamp 1.8.6 are separated, and the end mill under test is adapted to be clamped on the separated first clamp 1.8.5 and the second clamp 1.8.6; in the second state, the first clamp 1.8.5 and the second clamp 1.8.6 are close together, and the end mill under test is adapted to be removed from the first clamp 1.8.5 and the second clamp 1.8.6.

[0025] The milling cutter cutting edge defect detection device also includes: Rotating arm 1.8.2 is fixedly mounted on the output shaft of the second drive motor 1.8.9, and the center of the rotating arm 1.8.2 coincides with the output shaft of the second drive motor 1.8.9; A first pivot arm 1.8.4, one end of which is pivotally connected to the first chuck 1.8.3, and the other end of which is pivotally connected to one end of the rotating arm 1.8.2; The second pivot arm 1.8.7 has one end pivotally connected to the second jaw 1.8.8, and the other end pivotally connected to the other end of the rotating arm 1.8.2. When the second drive motor 1.8.9 rotates forward, it is adapted to drive the first jaw 1.8.3 and the second jaw 1.8.8 to move in a direction away from each other, so as to separate the first clamp 1.8.5 and the second clamp 1.8.6.

[0026] When the second drive motor 1.8.9 reverses, it is adapted to drive the first jaw 1.8.3 and the second jaw 1.8.8 to move toward each other, so that the first clamp 1.8.5 and the second clamp 1.8.6 move closer together.

[0027] The robotic arm 2 includes: Fixed base 2.1, which is connected and fixed to the worktable 1; The first connecting arm 2.3, one end of which is rotatably connected to the top of the fixed base 2.1 via the first motor 2.2; The second connecting arm 2.5, one end of which is rotatably connected to the other end of the first connecting arm 2.3 via the second motor 2.4; A snap-fit ​​connector 2.7 is rotatably connected to the other end of the second connecting arm 2.5 via a third motor 2.6. The ultrasonic transducer 3 is adapted to be snapped onto the snap-fit ​​connector 2.7. Through the movement of the robotic arm 2, when detecting the next blade to be tested, the ultrasonic transducer 3 can detach from the previous blade to be tested and abut against the next blade to be tested.

[0028] A method for detecting defects in the cutting edge of a milling cutter includes the following steps: S1: Based on the required geometric dimensions and material parameters of the milling cutter, and based on the three-dimensional linear elastic theory, consider an orthogonal isotropic pure elastic wedge. Establish a wave dynamics model of the wedge structure of the milling cutter cutting edge in the Cartesian coordinate system. Using the governing equations, constitutive equations, geometric relations, boundary conditions, and the expansion form of the Laguerre polynomial series, the Laguerre polynomial method for solving the wedge structure can be derived. Through this method, the group velocity dispersion curve of the wedge-shaped guided wave propagation can be calculated.

[0029] The calculated group velocity dispersion curve of the wedge-shaped guided wave propagating in the milling cutter cutting edge structure is as follows: By treating the milling cutter cutting edge as a single-layer wedge structure, the wave differential control equation can be derived based on the governing equation, geometric relations, constitutive equation and boundary conditions. Furthermore, by utilizing the orthogonality of the Laguerre polynomial series, the matrix equation relating the wave number k to the angular frequency ω can be obtained.

[0030] The governing equations are:

[0031] The geometric relationship is:

[0032] The constitutive equation is:

[0033] The boundary conditions are:

[0034] Laguerre polynomial series expansion form:

[0035] The matrix equation can be derived from the above equation:

[0036] In the formula, , These are the stress components and strain components, respectively, where α and β are variables (α, β = x1, x2, x3), and x1, x2, and x3 are the three coordinate axes of the Cartesian coordinate system (the wave propagation direction is the x3 direction). For displacement, , Displacement Displacement components in the α and β directions; , and These are the elastic constant, material density, and boundary slope, respectively. Stress components The first derivative with respect to β; For displacement components The first derivative with respect to β; For displacement components The first derivative with respect to α; For displacement components The second derivative with respect to time t; i is the imaginary unit, i.e., i = Both m and n are cycle orders; These are the expansion coefficients of the Laguerre polynomial; It is an m-th order Laguerre polynomial; It is an n-order Laguerre polynomial; A, B, C, and D are all... The n-order matrix; p is the eigenvector.

[0037] Numerical solutions using the above formulas can transform the wave problem into an eigenvalue problem. Substituting the solution into the group velocity calculation formula yields the group velocity dispersion curve.

[0038]

[0039] In the formula, The value is the group velocity, in m / s.

[0040] S2: Perform mode differentiation on the acquired group velocity dispersion curves and select the maximum group velocity value of a specific mode. The optimal excitation frequency for the guided wave detector is selected based on the group velocity dispersion curve. The standard for selecting a suitable excitation frequency is that the group velocity of the wedge-shaped guided wave is the largest at this excitation frequency, while the propagation speed of other guided wave modes is small. Since the mode corresponding to the maximum group velocity is easily distinguished from other modes during propagation, the frequencies at these positions are selected as the optimal excitation frequencies for guided wave experiments to facilitate analysis.

[0041] S3. Fix the milling cutter to be tested on the mounting base 1.8, start the milling cutter edge defect detection device, and connect the guided wave detector 4 to the ultrasonic transducer 3 on the snap-fit ​​2.7; the ultrasonic transducer 3 is used to realize the mutual conversion of electrical signals and mechanical vibrations; the ultrasonic transducer 3 is both the exciter and receiver of the wedge guided wave; after the ultrasonic transducer 3 receives the wedge guided wave signal, the guided wave detector 4 acquires the detected echo signal data. Through a calculation program, the time domain signal in the echo signal detected by the guided wave detector 4 is processed by wavelet transform to obtain wavelet coefficients of multiple frequency bands; then, one or more frequency bands of wavelet coefficients are selected for reconstruction to obtain a primary reconstructed signal; then, the primary reconstructed signal is denoised and the weak signal features are enhanced to obtain a secondary reconstructed signal; finally, the maximum amplitude value of the excitation signal and the defect reflection echo signal in the secondary reconstructed signal is extracted to obtain the time difference Δt of the blade structure defect reflection echo. S4. Based on the defect reflection echo time difference Δt obtained from the secondary reconstruction signal and the group velocity value of the wedge-shaped guided wave propagation. That is, the maximum group velocity The distance L between the defect location and the excitation end face of the milling cutter is calculated using the following formula; .

[0042] Example The end mill specimen in this embodiment is based on cemented carbide material, angle 20 degrees, thickness 8 mm, and density 7850 kg / m³. 3 Elastic constant C 11 C 12 C 44 The milling cutter cutting edge structures are 236.9631, 78.9877, and 78.9877 respectively.

[0043] The milling cutter's cutting edge structure can be considered as a single-layer wedge structure. Substituting the material's geometric parameters into the above equations, and using the Laguerre polynomial series analytical solution method, the wave problem is transformed into an eigenvalue problem, thus obtaining the group velocity dispersion curve, as shown below. Figure 2 As shown. Since the group velocity of the wedge-guided wave is highest at 253kHz, this frequency is most suitable for detection.

[0044] Combined with appendix Figure 1 Appendix Figure 3 Appendix Figure 4 and attached Figure 5 In the first step of the end mill under test in this embodiment, the second drive motor 1.8.9 on the worktable 1 drives the rotating arm 1.8.2, the first pivot arm 1.8.4, and the second pivot arm 1.8.7 to rotate, thereby driving the first clamp 1.8.5 and the first clamp 1.8.6 to move and fix the end mill under test; the first motor 2.2, the second motor 2.4, and the third motor 2.6 on the robotic arm 2 are started to drive the first connecting arm 2.3, the second connecting arm 2.5, and the clamping piece 2.7 to move, so that the ultrasonic transducer 3 coated with coupling agent is directly facing the end face of the end mill cutting edge; the end mill under test... In the second step of testing the milling cutter, the guided wave detector 4 uses a sinusoidal signal modulated by a Hanning window with a frequency of 253kHz and a period of 3 as the excitation signal to start the workbench 1, the robotic arm 2, and the guided wave detector 4 to test the milling cutter edge. In the third step of testing the milling cutter, the drive mechanism 1.2 on the workbench 1 is controlled to drive the rotating platform 1.3 to rotate, and the first motor 2.2, the second motor 2.4, and the third motor 2.6 on the robotic arm 2 are started to drive the first connecting arm 2.3, the second connecting arm 2.5, and the locking piece 2.7 to move relative to each other, so as to realize the health test of each milling cutter edge.

[0045] Combined with appendix Figure 1 and attached Figure 6 In this embodiment, the number of ultrasonic transducers 3 determined by the end face of the milling cutter is 1, and one ultrasonic transducer 3 is positioned directly opposite the end face of the milling cutter cutting edge. The guided wave detector 4 amplifies the excitation signal and the reflected echo signal to enhance the detection of wedge-shaped guided waves with minute defects.

[0046] Combined with appendix Figure 7In this embodiment, a waveform diagram of a 253kHz wedge-shaped guided wave propagating in a defective milling cutter edge is shown. The defect has dimensions of 0.2mm depth and 0.1mm width, and is located 4mm from the signal excitation end. It can be seen that due to the presence of the defect, there is a defective reflected echo packet between the end-face reflected echo and the excitation signal.

[0047] Combined with appendix Figure 1 and, attached Figure 8 and attached Figure 9 In this embodiment, based on the experimental data obtained from the detection, a calculation program written in MATLAB is used to perform wavelet transform processing on the time-domain signal of the echo signal detected by the guided wave detector to obtain wavelet coefficients in multiple frequency bands. Then, the wavelet coefficients at the defect location are selected for reconstruction to obtain a first-reconstructed signal. The first-reconstructed signal is then denoised and its weak signal features are enhanced to obtain a second-reconstructed signal. Finally, features are extracted from the maximum amplitude of the excitation signal and the defect reflection echo signal in the second-reconstructed signal to obtain the time difference of the blade structure defect reflection echo. t, Δt=tt d , where t, t d These represent the time corresponding to the maximum amplitude of the defect reflection echo signal in the secondary reconstruction signal and the time corresponding to the maximum amplitude of the excitation signal in the secondary reconstruction signal, respectively.

[0048] Based on the defect reflection echo time difference Δt obtained from the secondary reconstructed signal and the group velocity value of the wedge-guided wave propagation... The distance L between the defect location and the excitation end face of the milling cutter was calculated to be 4.1 mm using the following formula, with an error of 2.5% compared to the actual location; The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Those skilled in the art will recognize various modifications and variations that can be made to the present invention. Any substitutions, improvements, or modifications made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0049] Any aspects of this invention not described in detail are well-known to those skilled in the art.

Claims

1. A device for detecting defects in a milling cutter blade, characterized in that, The milling cutter edge defect detection device comprises a workbench, a mechanical arm, an ultrasonic transducer and a guided wave detector. The workbench is provided with a mounting seat for a milling cutter to be detected, and the milling cutter to be detected is detachably mounted on the mounting seat. The mechanical arm is installed at one end of the workbench and is spaced apart from the mounting seat. The ultrasonic transducer is installed at a free end of the mechanical arm, and the mechanical arm is adapted to drive the ultrasonic transducer to move opposite to an edge end face of the milling cutter to be detected. The guided wave detector is arranged on the workbench and is electrically connected to the ultrasonic transducer.

2. The device for detecting defects of a milling cutter blade according to claim 1, characterized in that, The guided wave detector is used to excite and receive signals of a preset frequency. The workbench comprises support legs, a top plate, a bottom plate and a rotating platform. The support legs are parallel and spaced apart along the circumferential direction of the workbench. The top plate is connected to the top ends of the support legs and is formed with a through hole. The center axis of the through hole is perpendicular to the top plate. The mechanical arm and the guided wave detector are arranged on the top plate.

3. The device of claim 2, wherein, The bottom plate is parallel and spaced apart from the top plate. The bottom plate is connected to the support legs. The bottom plate and the support legs are spaced apart from each other at the ends away from the top plate.

4. The device of claim 2, wherein, The bottom plate, the top plate and the support legs jointly define a mounting cavity. The through hole is in communication with the mounting cavity. The rotating platform is partially arranged in the mounting cavity. The center axis of the rotating platform coincides with the center axis of the through hole. The end of the rotating platform away from the bottom plate is located on the upper side of the top plate. The mounting seat is fixedly arranged on the rotating platform. The center axis of the mounting seat coincides with the center axis of the through hole. The drive mechanism is arranged in the mounting cavity. The drive mechanism is connected to the rotating platform and is adapted to drive the rotating platform to rotate. The drive mechanism comprises a first drive motor and a transmission disc. The first drive motor is arranged in the mounting cavity and is spaced apart from the through hole in the length direction of the top plate. The transmission disc is rotatably arranged in the mounting cavity and the center axis of the transmission disc coincides with the center axis of the through hole. The first drive mechanism drives the transmission disc to rotate through a transmission belt. The rotating platform is fixed to the transmission disc. The mounting seat is provided with a first sliding channel and a second sliding channel located on the same straight line. The milling cutter edge defect detection device further comprises a first jaw, a second jaw and a second drive motor. One end of the first jaw is movably clamped in the first sliding channel. The other end of the first jaw is formed with a first clamp. One end of the second jaw is movably clamped in the second sliding channel. The other end of the second jaw is formed with a second clamp. The second drive motor is arranged on the mounting seat and is located at the end of the first sliding channel and the second sliding channel facing each other. The center axis of the second drive motor coincides with the center axis of the mounting seat. The second driving motor is adapted to drive the first claw to move along the first slide rail and drive the second claw to move along the second slide rail, so that the first claw and the second claw are switched between a first state and a second state; in the first state, the first claw and the second claw are separated, and the to-be-tested milling cutter is adapted to be clamped on the separated first claw and second claw; in the second state, the first claw and the second claw are close to each other, and the to-be-tested milling cutter is adapted to be removed from the first claw and the second claw.

5. The device of claim 2, wherein, The milling cutter edge defect detection device further comprises: a rotating arm fixedly arranged on an output shaft of the second driving motor, and a center of the rotating arm coincides with the output shaft of the second driving motor; a first pivoting arm, one end of the first pivoting arm being pivotably connected with the first claw, and the other end of the first pivoting arm being pivotably connected with one end of the rotating arm; a second pivoting arm, one end of the second pivoting arm being pivotably connected with the second claw, and the other end of the second pivoting arm being pivotably connected with the other end of the rotating arm, wherein, when the second driving motor rotates forward, the first claw and the second claw are adapted to move in a direction away from each other, so that the first claw and the second claw are separated; when the second driving motor reverses, the first claw and the second claw are adapted to move in a direction towards each other, so that the first claw and the second claw are close to each other.

6. The device of claim 1, wherein, The mechanical arm comprises: a fixed seat connected and fixed on the workbench; a first connecting arm, one end of the first connecting arm being rotatably connected to a top end of the fixed seat by a first motor; a second connecting arm, one end of the second connecting arm being rotatably connected to the other end of the first connecting arm by a second motor; a clamping piece, the clamping piece being rotatably connected to the other end of the second connecting arm by a third motor, and the ultrasonic transducer being adapted to be clamped on the clamping piece.

7. A defect detection method based on the cutter blade defect detection apparatus according to any one of claims 1 to 6, characterized by, The defect detection method comprises: S1: based on three-dimensional linear elasticity theory, a wave mechanics model with the same material and wedge angle as the structure of the to-be-tested milling cutter edge is established, and a double-Laguerre polynomial series analytical solution method is adopted to obtain a group velocity dispersion curve of wedge-shaped guided wave propagation in the wave mechanics model; S2: modal distinction is made to the acquired group velocity dispersion curve, and a specific modal group velocity maximum value is selected as the optimal excitation frequency detected by the guided wave detector S3: fixing the to-be-tested milling cutter on the mounting seat, starting the milling cutter edge defect detection device, obtaining a return signal detected by the guided wave detector, and calculating a defect reflection return time difference Δt; S4: determining a group velocity value of the wedge-shaped guided wave propagation based on the defect reflection time difference Δt The position of the defect of the cutter blade structure is determined.

8. The defect detection method of claim 7, wherein, The calculation of the defect reflection return time difference Δt comprises: S31: performing wavelet transform processing on the time domain signal of the return signal detected by the guided wave detector to obtain wavelet coefficients of multiple frequency bands; S32: selecting one or more frequency band wavelet coefficients to reconstruct to obtain a first reconstructed signal; S33: obtaining a secondary reconstruction signal by de-noising the primary reconstruction signal and strengthening weak signal characteristics, obtaining times corresponding to maximum amplitudes of the excitation signal and the defect reflection echo signal in the secondary reconstruction signal as t d and t, that is, t-t d is the defect reflection echo time difference Δt of the milling cutter edge.

9. The defect detection method according to claim 7, wherein, in step S4, the distance L between the defect position and the milling cutter excitation end face is calculated by using the following formula: 。

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