A system and method for locating vibration sensitive points of an electric spindle based on noise detection

Abstract

The present invention discloses a system and method for locating vibration sensitive points of an electric spindle based on noise detection. The platform base of the system is installed on the top surface of the support frame through a support plate, the electric spindle fixing seat is installed on the top surface of the platform base, the electric spindle is installed on the electric spindle fixing seat, and the sensor assembly is installed on the platform base. The method includes: installing the electric spindle and the microphone; receiving the noise signal generated by the electric spindle through the microphone; obtaining the sound pressure level of the noise generated in the noise test area, and obtaining the orientation of the noise source after filtering, weighting and sound source array processing of the noise signal; determining the vibration sensitive point of the electric spindle based on the sound pressure level and orientation to achieve positioning. The present invention combines the noise characteristics and vibration characteristics of the electric spindle, determines the vibration sensitive point of the electric spindle based on the orientation of the noise source and the noise sound pressure level, solves the problem of incomplete selection of vibration sensitive points and difficulty in accurately grasping the overall vibration characteristics of the electric spindle, and can improve the accuracy of the vibration data of the electric spindle.

Description

Technical Field

[0001] The present invention relates to a vibration sensitive point positioning system, and in particular to a vibration sensitive point positioning system and method for an electric spindle based on noise detection. Background Art

[0002] As a core component of high-speed machine tools, high-speed electric spindles rely on motors to directly drive the spindle's rotation. Due to machining and assembly errors, the electric spindle typically vibrates during operation. This vibration can affect the electric spindle's performance, thereby reducing the machine tool's machining accuracy and service life. Therefore, the electric spindle is generally tested for vibration characteristics before leaving the factory. The vibration characteristics testing process for an electric spindle is generally as follows: 1) Secure the electric spindle; 2) Select a vibration sensor and arrange vibration measurement points; 3) Start the electric spindle and conduct a vibration test experiment; 4) Analyze the vibration test data and evaluate the vibration characteristics of the electric spindle.

[0003] Precisely locating the vibration-sensitive points of an electric spindle can effectively improve the accuracy of vibration characteristic testing. There are two main approaches to selecting vibration-sensitive points. One method involves installing vibration sensors at the front and rear end bearings of the electric spindle and determining the vibration characteristics of the electric spindle by measuring the vibration at the bearings. The other method involves setting a large number of measurement points on the electric spindle housing to collect vibration data at different speeds. The measurement points with the largest amplitudes are then identified as vibration-sensitive points to further evaluate the vibration characteristics of the electric spindle.

[0004] It can be seen that the current method of locating the vibration-sensitive points of the electric spindle has the following limitations: 1) If only the front and rear bearings of the electric spindle are selected as vibration-sensitive points, it is difficult to accurately grasp the overall vibration characteristics of the electric spindle; 2) If the vibration-sensitive points are determined by setting a large number of measuring points on the electric spindle housing, the operation process is cumbersome and costly, which is not suitable for practical application. Summary of the Invention

[0005] In order to solve the problems existing in the background technology, the present invention provides a system and method for locating the vibration sensitive points of an electric spindle based on noise detection. The noise during the operation of the electric spindle is collected by a microphone, and the vibration sensitive points are determined according to the measured noise source and sound pressure level, which effectively solves the problems of difficulty in locating the vibration sensitive points of the electric spindle and the cumbersome positioning process.

[0006] The technical solution adopted in the present invention is:

[0007] 1. A vibration sensitive point positioning system for an electric spindle based on noise detection:

[0008] The system includes a support plate, a support frame, a platform base, a sensor assembly and an electric spindle fixing seat. The platform base is installed on the top surface of the support frame through a horizontal support plate. The electric spindle fixing seat is installed on the top surface of the platform base. A horizontally arranged electric spindle to be tested is installed on the electric spindle fixing seat. The sensor assembly is installed on the platform base and is located on one side in the length direction of the electric spindle. The sensor assembly is electrically connected to an external signal collector and is electrically connected to an external computer device through the external signal collector.

[0009] The sensor assembly includes a sensor mounting bracket, two sensor mounting plates, and several microphones. The sensor mounting bracket is installed on the platform base and is located on one side of the length direction of the electric spindle. One of the sensor mounting plates is installed on the top surface of the sensor mounting bracket and is parallel to the length direction of the electric spindle. The other sensor mounting plate is installed on the side of the sensor mounting bracket away from the electric spindle and is parallel to the length direction of the electric spindle. Each microphone is vertically installed on one of the sensor mounting plates or horizontally installed on the other sensor mounting plate and is arranged parallel to each other and evenly spaced along the length direction of the sensor mounting plates. The pickup at the end of each microphone is arranged opposite to the same side of the electric spindle and is spaced apart. Each microphone is electrically connected to an external signal collector and is electrically connected to an external computer device through the external signal collector.

[0010] The electric spindle is evenly divided into several noise test areas along its length, and each noise test area faces the pickup at the end of a respective microphone; the number of microphones is the same as the number of noise test areas, and the number of microphones is greater than or equal to three.

[0011] The top surface of the sensor mounting bracket is provided with two rows of evenly spaced first threaded holes in parallel and horizontally on both sides of the symmetrical sides, and the side surface of the sensor mounting bracket away from the electric spindle is provided with two rows of evenly spaced second threaded holes in parallel and vertically on both sides of the symmetrical sides. One of the sensor mounting plates is installed on the top surface of the sensor mounting bracket through each first threaded hole and a number of screws, and the other sensor mounting plate is installed on the side surface of the sensor mounting bracket away from the electric spindle through each second threaded hole and a number of screws; the position of the sensor mounting plate is adjusted, thereby adjusting the position of the microphone, so as to measure the noise sound pressure at different positions of the electric spindle.

[0012] 2. A method for locating a vibration sensitive point of an electric spindle in a vibration sensitive point positioning system includes the following steps:

[0013] 1) Install the electric spindle to be tested on the electric spindle fixing seat, install each microphone on the sensor mounting plate, and adjust the position of the sensor mounting plate so that each noise test area is facing the pickup at the end of each microphone.

[0014] 2) driving the electric spindle to operate, receiving noise signals generated by the electric spindle through each microphone, collecting the noise signals of each microphone through an external signal collector and transmitting them to an external computer device.

[0015] 3) The external computer device obtains the sound pressure level of the noise generated by the noise test area facing each microphone based on the noise signal collected by each microphone, and obtains the direction of the noise source detected by each microphone after filtering, weighting and sound source array processing on the noise signal collected by each microphone.

[0016] 4) The vibration sensitive point of the electric spindle is determined based on the sound pressure level of the noise generated in the noise test area facing each microphone and the direction of the detected noise source, thereby locating the vibration sensitive point of the electric spindle.

[0017] After positioning is completed, the vibration sensor can be placed at the selected vibration sensitive point to test the vibration of the electric spindle. After the test is completed, the detection of the next electric spindle can be continued.

[0018] In step 3), the sound pressure level of the noise generated by the noise test area facing each microphone is obtained according to the noise signal collected by each microphone, as follows:

[0019]

[0020] Among them, L Pi is the sound pressure level of the noise generated in the noise test area facing the i-th microphone; P i is the sound pressure of the noise generated in the noise test area facing the i-th microphone; P0 is the reference sound pressure.

[0021] In the step 3), the noise signal collected from each microphone is filtered and weighted, specifically filtering and weighting the cross power spectrum of the noise received by each microphone to obtain the noise signal generated by the mechanical vibration of the electric spindle.

[0022] In step 3), the direction of the noise source is obtained after performing sound source array processing. Specifically, for each microphone, the direction of a noise source detected by the microphone is calculated based on the noise signal generated by the mechanical vibration of the electric spindle obtained after filtering and weighting the noise received by the microphone and the other two microphones in each microphone, as follows:

[0023]

[0024] Among them, τ ij is the time delay between the i-th microphone and the j-th microphone receiving the noise signal emitted by the noise source; τ ikis the time delay between the i-th microphone and the k-th microphone receiving the noise signal emitted by the noise source; r i 、r j and r k are the distances between the noise source and the i-th, j-th, and k-th microphones, respectively; c is the speed of sound; d ij is the distance between the i-th microphone and the j-th microphone; d ik is the distance between the i-th microphone and the k-th microphone; θ is the angle between the noise source and the i-th microphone.

[0025] The direction of the noise source detected by the i-th microphone is finally obtained according to the angle θ between the noise source and the i-th microphone and the distances between the noise source and the i-th, j-th and k-th microphones.

[0026] First, the filtered weighted cross-power spectrum is inverse Fourier transformed into the time domain to obtain the time delay between the microphones and the noise signals they receive. Then, the angle and distance from the sound source to the microphones are calculated based on the geometric relationship between the noise source and the microphone array model to obtain the direction of the noise source.

[0027] The time delay τ between the i-th microphone and the j-th microphone receiving the noise signal emitted by the noise source ij The details are as follows:

[0028]

[0029] Among them, ω is the integral variable in the frequency domain; ψ ij () is the frequency domain weighting function of the cross power spectrum of the noise received by the i-th microphone and the j-th microphone; X i () is the Fourier transform of the cross-power spectrum of the noise received by the i-th microphone after filtering and weighting; is the conjugate of the Fourier transform of the cross-power spectrum of the noise received by the j-th microphone after filtering and weighting; e is a natural constant; and l is an imaginary unit.

[0030] In the step 4), the vibration sensitive point of the electric spindle is determined based on the sound pressure level of the noise generated in the noise test area facing each microphone and the orientation of the detected noise source. Specifically, based on the orientation of a noise source detected by each microphone, when two or more noise sources have the same orientation, the noise sources with the same orientation are used as the vibration sensitive points of the electric spindle; when the orientations of the noise sources are different, the noise test areas in which they are located and the sound pressure levels of the noise they generate are determined according to the orientations of the noise sources, and the noise sources on the noise test areas corresponding to the maximum values ​​of the sound pressure levels are selected as the vibration sensitive points of the electric spindle to achieve the positioning of the vibration sensitive points of the electric spindle.

[0031] The beneficial effects of the present invention are:

[0032] 1. The present invention combines the noise characteristics and vibration characteristics of the electric spindle, and determines the vibration sensitive points of the electric spindle according to the noise source distribution and noise sound pressure. This solves the problem of incomplete selection of vibration sensitive points and difficulty in accurately grasping the overall vibration characteristics of the electric spindle, and can improve the accuracy of the electric spindle vibration data.

[0033] 2. The present invention combines a microphone with a vibration sensor and uses an appropriate number of sensors to obtain the vibration sensitive points of the electric spindle, which simplifies the operation process, greatly reduces the experimental cost, and has guiding significance for practical applications.

[0034] 3. The sensor mounting assembly designed in the present invention can be adjusted to different heights, lengths and distances, measure the noise distribution of various parts of the electric spindle, determine the vibration sensitive points of various parts of the electric spindle, and at the same time realize the positioning of vibration sensitive points of electric spindles of different sizes. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is an overall three-dimensional structural diagram of a test system according to a preferred embodiment of the present invention;

[0036] Figure 2 is a three-dimensional assembly diagram of a sensor mounting assembly according to a preferred embodiment of the present invention;

[0037] Figure 3 is a flow chart of a testing method according to a preferred embodiment of the present invention;

[0038] Figure 4 is a noise source location diagram of a preferred embodiment of the present invention;

[0039] In the figure: 1. Support plate, 2. Support frame, 3. Electric spindle, 4. Platform base, 5. Sensor mounting bracket, 6. Sensor mounting plate, 7. Microphone, 8. Electric spindle fixing seat, 9. Vibration sensor. DETAILED DESCRIPTION

[0040] The present invention will be further described below with reference to the accompanying drawings and examples. It should be noted that the following examples are intended to facilitate understanding of the present invention and do not have any limiting effect on the present invention.

[0041] like Figure 1As shown, the electric spindle vibration sensitive point positioning system of the present invention includes a support plate 1, a support frame 2, a platform base 4, a sensor assembly and an electric spindle fixing seat 8. The platform base 4 is installed on the top surface of the support frame 2 through the horizontal support plate 1, and the electric spindle fixing seat 8 is installed on the top surface of the platform base 4. A horizontally arranged electric spindle 3 to be detected is installed on the electric spindle fixing seat 8. The sensor assembly is installed on the platform base 4 and is located on one side of the length direction of the electric spindle 3. The sensor assembly is electrically connected to an external signal collector and is electrically connected to an external computer device through the external signal collector.

[0042] The sensor assembly includes a sensor mounting bracket 5, two sensor mounting plates 6, and several microphones 7. The sensor mounting bracket 5 is mounted on the platform base 4 and is located on one side of the length direction of the electric spindle 3. One of the sensor mounting plates 6 is mounted on the top surface of the sensor mounting bracket 5 and is parallel to the length direction of the electric spindle 3. The other sensor mounting plate 6 is mounted on a side of the sensor mounting bracket 5 away from the electric spindle 3 and is parallel to the length direction of the electric spindle 3. Each microphone 7 is vertically mounted on one of the sensor mounting plates 6 or horizontally mounted on the other sensor mounting plate 6 and is arranged parallel to each other and evenly spaced along the length direction of the sensor mounting plates 6. The pickup at the end of each microphone 7 is arranged opposite to the same side of the electric spindle 3 and is spaced apart. Each microphone 7 is electrically connected to an external signal collector and is electrically connected to an external computer device through the external signal collector.

[0043] The electric spindle 3 is evenly divided into several noise test areas along its length, and each noise test area faces the pickup at the end of a respective microphone 7; the number of microphones 7 is the same as the number of noise test areas, and the number of microphones is greater than or equal to three.

[0044] like Figure 2 As shown, two rows of evenly spaced first threaded holes are opened horizontally and parallel on both symmetrical sides of the top surface of the sensor mounting bracket 5, and two rows of evenly spaced second threaded holes are opened vertically and parallel on both symmetrical sides of the side of the sensor mounting bracket 5 away from the electric spindle 3. One sensor mounting plate 6 is installed on the top surface of the sensor mounting bracket 5 through each first threaded hole and a number of screws, and the other sensor mounting plate 6 is installed on the side of the sensor mounting bracket 5 away from the electric spindle 3 through each second threaded hole and a number of screws; the position of the sensor mounting plate 6 is adjusted, thereby adjusting the position of the microphone 7 to measure the noise pressure at different positions of the electric spindle 3. Figure 2As shown, the sensor mounting assembly includes two sensor brackets 5, two sensor mounting plates 6, and a microphone 7. The sensor mounting brackets 5 are provided with multiple threaded holes. The two sensor mounting brackets 6 are arranged in parallel and mounted on the platform base 4 via T-shaped holes at their bases. One sensor mounting plate 6 is mounted on the upper side of the sensor mounting bracket 5, while the other is mounted on the rear side of the sensor mounting bracket 5. U-shaped grooves are provided on both sides of the sensor mounting plates 6 for adjusting the mounting position of the sensor mounting plates 6.

[0045] like Figure 3 As shown, the method for locating the vibration sensitive point of an electric spindle of the electric spindle vibration sensitive point positioning system of the present invention comprises the following steps:

[0046] 1) Install the electric spindle 3 to be tested on the electric spindle fixing seat 8, install each microphone 7 on the sensor mounting plate 6, and adjust the position of the sensor mounting plate 6 so that each noise test area is facing the pickup at the end of each microphone 7.

[0047] 2) driving the electric spindle 3 to operate, receiving noise signals generated by the electric spindle 3 through each microphone 7, collecting the noise signals of each microphone 7 through an external signal collector and transmitting them to an external computer device.

[0048] 3) The external computer device obtains the sound pressure level of the noise generated by the noise test area facing each microphone 7 based on the noise signal collected by each microphone 7, and obtains the direction of the noise source detected by each microphone 7 after filtering, weighting and sound source array processing on the noise signal collected by each microphone 7.

[0049] In step 3), the sound pressure level of the noise generated by the noise test area facing each microphone 7 is obtained according to the noise signal collected, as follows:

[0050]

[0051] Among them, L Pi is the sound pressure level of the noise generated by the noise test area facing the i-th microphone 7; P i is the sound pressure of the noise generated in the noise test area facing the i-th microphone 7; P0 is the reference sound pressure.

[0052] In step 3), filtering and weighting processing is performed on the noise signal collected by each microphone 7. Specifically, the cross power spectrum of the noise received by each microphone 7 is filtered and weighted to obtain the noise signal generated by the mechanical vibration of the electric spindle 3.

[0053] In step 3), the direction of the noise source is obtained after performing sound source array processing. Specifically, for each microphone 7, the direction of a noise source detected by the microphone 7 is calculated based on the noise signal generated by the mechanical vibration of the electric spindle 3 obtained by filtering and weighting the noise received by the microphone 7 and the other two microphones 7 in each microphone 7, as follows:

[0054]

[0055] Among them, τ ij is the time delay between the i-th microphone 7 and the j-th microphone 7 receiving the noise signal emitted by the noise source; τ ik is the time delay between the i-th microphone 7 and the k-th microphone 7 receiving the noise signal emitted by the noise source; r i 、r j and r k are the distances between the noise source and the i-th, j-th and k-th microphones 7, respectively; c is the speed of sound; d ij is the distance between the i-th microphone 7 and the j-th microphone 7; d ik is the distance between the i-th microphone 7 and the k-th microphone 7; θ is the angle between the noise source and the i-th microphone 7.

[0056] The direction of the noise source detected by the i-th microphone 7 is finally obtained according to the angle θ between the noise source and the i-th microphone 7 and the distances between the noise source and the i-th, j-th and k-th microphones 7 .

[0057] First, the filtered weighted cross-power spectrum is inverse Fourier transformed into the time domain to obtain the time delay between microphone 7 and the noise signal received by each microphone. Then, the angle and distance from the sound source to microphone 7 are calculated based on the geometric relationship between the noise source and the microphone array model to obtain the direction of the noise source.

[0058] The time delay τ between the i-th microphone 7 and the j-th microphone 7 receiving the noise signal emitted by the noise source ij The details are as follows:

[0059]

[0060] Among them, ω is the integral variable in the frequency domain; ψ ij () is the frequency domain weighting function of the cross power spectrum of the noise received by the i-th microphone 7 and the j-th microphone 7; X i () is the Fourier transform of the cross-power spectrum of the noise received by the i-th microphone 7 after filtering and weighting; is the conjugate of the Fourier transform of the cross-power spectrum of the noise received by the j-th microphone 7 after filtering and weighting; e is a natural constant; and l is an imaginary unit.

[0061] 4) The vibration sensitive point of the electric spindle 3 is determined based on the sound pressure level of the noise generated in the noise test area facing each microphone 7 and the direction of the detected noise source, thereby locating the vibration sensitive point of the electric spindle 3.

[0062] In step 4), the vibration sensitive point of the electric spindle 3 is determined based on the sound pressure level of the noise generated in the noise test area facing each microphone 7 and the orientation of the detected noise source. Specifically, based on the orientation of a noise source detected by each microphone 7, when two or more noise sources have the same orientation, the noise sources with the same orientation are used as the vibration sensitive points of the electric spindle 3; when the orientations of the noise sources are different, the noise test areas in which they are located and the sound pressure levels of the noises they generate are determined according to the orientations of the noise sources, and the noise sources on the noise test areas corresponding to the maximum values ​​of the sound pressure levels are selected as the vibration sensitive points of the electric spindle 3 to achieve the positioning of the vibration sensitive points of the electric spindle 3.

[0063] After the positioning is completed, the vibration sensor 9 can be placed at the selected vibration sensitive point to test the vibration of the electric spindle 3. After the test is completed, the detection of the next electric spindle 3 can be continued.

[0064] The specific embodiments of the present invention are as follows:

[0065] In the specific implementation, the noise test area of ​​the electric spindle 3 is divided as follows: 20 cm above the upper end face of the electric spindle 3 is taken as the upper measuring surface, 20 cm to the left of the left end face is taken as the left measuring surface, four microphones 7 are equidistantly arranged at the central axis of the electric spindle 3 corresponding to each measuring surface, and the sensor mounting plate 6 is moved to the corresponding position.

[0066] like Figure 4 As shown, based on the time delay between three adjacent microphones and the geometric relationship of the microphone array, the specific calculation method of the noise source direction is:

[0067]

[0068] Among them, τ 12 is the time delay between the first microphone 7 and the second microphone 7, τ 13 is the time delay between the first microphone 7 and the third microphone 7; r1, r2, and r3 are the distances from the noise source to the first, second, and third microphones 7, respectively; d is the distance between two adjacent microphones 7; c is the speed of sound; and θ is the angle between the noise source and the first microphone 7. The direction of the noise source can be determined based on the obtained angle θ and the distances r1, r2, and r3.

[0069] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A vibration sensitive point positioning system for an electric spindle based on noise detection, characterized by: The invention comprises a support plate (1), a support frame (2), a platform base (4), a sensor assembly and an electric spindle fixing seat (8), wherein the platform base (4) is mounted on the top surface of the support frame (2) through the horizontal support plate (1), the electric spindle fixing seat (8) is mounted on the top surface of the platform base (4), a horizontally arranged electric spindle (3) to be detected is mounted on the electric spindle fixing seat (8), the sensor assembly is mounted on the platform base (4) and is located on one side in the length direction of the electric spindle (3), and the sensor assembly is electrically connected to an external signal collector and electrically connected to an external computer device through the external signal collector; The sensor assembly comprises a sensor mounting bracket (5), two sensor mounting plates (6), and a plurality of microphones (7). The sensor mounting bracket (5) is mounted on the platform base (4) and is located on one side of the length direction of the electric spindle (3). One of the sensor mounting plates (6) is mounted on the top surface of the sensor mounting bracket (5) and is parallel to the length direction of the electric spindle (3). The other sensor mounting plate (6) is mounted on a side of the sensor mounting bracket (5) away from the electric spindle (3) and is parallel to the length direction of the electric spindle (3). Each microphone (7) is vertically mounted on one of the sensor mounting plates (6) or horizontally mounted on the other sensor mounting plate (6) and is arranged parallel to each other and evenly spaced along the length direction of the sensor mounting plates (6). The pickup at the end of each microphone (7) is arranged opposite to the same side of the electric spindle (3) and is spaced apart. Each microphone (7) is electrically connected to an external signal collector and electrically connected to an external computer device through the external signal collector. Two rows of evenly spaced first threaded holes are provided horizontally and in parallel on both symmetrical sides of the top surface of the sensor mounting bracket (5), and two rows of evenly spaced second threaded holes are provided vertically and in parallel on both symmetrical sides of the side surface of the sensor mounting bracket (5) away from the electric spindle (3). One of the sensor mounting plates (6) is mounted on the top surface of the sensor mounting bracket (5) through each of the first threaded holes and a plurality of screws, and the other sensor mounting plate (6) is mounted on the side surface of the sensor mounting bracket (5) away from the electric spindle (3) through each of the second threaded holes and a plurality of screws.

2. The electric spindle vibration sensitive point positioning system based on noise detection according to claim 1, characterized in that: The electric spindle (3) is evenly divided into a plurality of noise test areas along its length direction, and each noise test area faces the pickup at the end of a respective microphone (7); the number of microphones (7) is the same as the number of noise test areas, and the number of microphones is greater than or equal to three.

3. The method for locating the vibration sensitive point of an electric spindle according to any one of claims 1 to 2, characterized in that: The method comprises the following steps: 1) Install the electric spindle (3) to be tested on the electric spindle fixing seat (8), install each microphone (7) on the sensor mounting plate (6), and adjust the position of the sensor mounting plate (6) so that each noise test area is directly opposite to the pickup at the end of each microphone (7); 2) driving the electric spindle (3) to operate, receiving noise signals generated by the electric spindle (3) through each microphone (7), collecting the noise signals of each microphone (7) through an external signal collector and transmitting the noise signals to an external computer device; 3) The external computer device obtains the sound pressure level of the noise generated by the noise test area facing each microphone (7) based on the noise signal collected by each microphone (7), and obtains the direction of the noise source detected by each microphone (7) after performing filtering weighting processing and sound source array processing on the noise signal collected by each microphone (7); 4) The vibration sensitive point of the electric spindle (3) is determined based on the sound pressure level of the noise generated in the noise test area facing each microphone (7) and the direction of the detected noise source, thereby realizing the positioning of the vibration sensitive point of the electric spindle (3).

4. The method for locating the vibration sensitive point of an electric spindle of the electric spindle vibration sensitive point positioning system according to claim 3, characterized in that: In the step 3), the sound pressure level of the noise generated by the noise test area facing each microphone (7) is obtained according to the noise signal collected, as follows: in, is the sound pressure level of the noise generated in the noise test area facing the i-th microphone (7); is the sound pressure of the noise generated in the noise test area facing the i-th microphone (7); is the reference sound pressure.

5. The method for locating the vibration sensitive point of an electric spindle of the electric spindle vibration sensitive point positioning system according to claim 3, characterized in that: In the step 3), the noise signal collected by each microphone (7) is filtered and weighted, specifically filtering and weighting the cross-power spectrum of the noise received by each microphone (7) to obtain the noise signal generated by the mechanical vibration of the electric spindle (3).

6. The method for locating the vibration sensitive point of an electric spindle of the electric spindle vibration sensitive point positioning system according to claim 5, characterized in that: In the step 3), the orientation of the noise source is obtained after performing sound source array processing. Specifically, for each microphone (7), the orientation of a noise source detected by the microphone (7) is calculated based on the noise signal generated by the mechanical vibration of the electric spindle (3) obtained after filtering and weighting the noise received by each microphone (7) and the other two microphones (7) in each microphone (7), as follows: in, is the time delay between the i-th microphone (7) and the j-th microphone (7) receiving the noise signal emitted by the noise source; is the time delay between the i-th microphone (7) and the k-th microphone (7) receiving the noise signal emitted by the noise source; 、 and are the distances between the noise source and the i-th, j-th and k-th microphones (7), respectively; is the speed of sound; is the distance between the i-th microphone (7) and the j-th microphone (7); is the distance between the i-th microphone (7) and the k-th microphone (7); is the angle between the noise source and the i-th microphone (7); According to the angle between the noise source and the i-th microphone (7) As well as the distances between the noise source and the i-th, j-th and k-th microphones (7), the orientation of the noise source detected by the i-th microphone (7) is finally obtained.

7. The method for locating the vibration sensitive point of an electric spindle of the electric spindle vibration sensitive point positioning system according to claim 6, characterized in that: The time delay between the i-th microphone (7) and the j-th microphone (7) receiving the noise signal emitted by the noise source The details are as follows: in, is the integral variable in the frequency domain; is the frequency domain weighting function of the cross power spectrum of the noise received by the i-th microphone (7) and the j-th microphone (7); is the Fourier transform of the cross-power spectrum of the noise received by the i-th microphone (7) after filtering and weighting; is the conjugate of the Fourier transform of the cross-power spectrum of the noise received by the j-th microphone (7) after filtering and weighting; e is a natural constant; l is an imaginary unit.

8. The method for locating the vibration sensitive point of an electric spindle of the electric spindle vibration sensitive point positioning system according to claim 6, characterized in that: In the step 4), the vibration sensitive point of the electric spindle (3) is determined based on the sound pressure level of the noise generated in the noise test area facing each microphone (7) and the orientation of the detected noise source. Specifically, based on the orientation of a noise source detected by each microphone (7), when two or more noise sources have the same orientation, the noise sources with the same orientation are used as the vibration sensitive point of the electric spindle (3); when the orientations of the noise sources are different, the noise test areas in which they are located and the sound pressure levels of the noise they generate are determined based on the orientations of the noise sources, and the noise source on the noise test area corresponding to the maximum value of the sound pressure levels is selected as the vibration sensitive point of the electric spindle (3), thereby realizing the positioning of the vibration sensitive point of the electric spindle (3).

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