Method and system for suppressing low-frequency resonance of press machine

Abstract

The invention provides a low-frequency resonance suppression method and system for a press machine, and the method comprises the following steps: obtaining a multi-order modal shape and a corresponding vibration frequency of the press machine through finite element analysis and vibration testing; the method comprises the steps that the vibration frequency ranges of different component positions of a press entity are determined, at least one set of three-axis acceleration sensors and resonance suppression units are arranged at the comprehensive vibration frequency peak position in the press entity, and each resonance suppression unit comprises nonlinear dynamic vibration absorbers distributed along the x axis, the y axis and the z axis; the three-axis acceleration sensor periodically collects vibration signals of the press machine, the resonance frequency of the press machine in the three-axis direction is obtained through calculation, the vibration control efficiency of the non-linear dynamic vibration absorbers distributed along the x axis, the y axis and the z axis is correspondingly adjusted, and the low-frequency resonance frequency of the press machine in the vertical direction and the horizontal direction is restrained to be within the preset range. According to the invention, the resonance dynamic suppression function of the press machine in the vertical direction and the horizontal direction can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of presses, and particularly relates to a method and system for suppressing low-frequency resonance of a press. Background Art

[0002] A press is a mechanical device widely used in industrial manufacturing, mainly used in processes such as metal forming, stamping, and die forging. It can apply high pressure to cause plastic deformation of materials, thereby producing required parts or products with special shapes.

[0003] Any press has a resonance frequency, which is determined by the physical properties such as the mass and stiffness of each component of the press. When the frequency of the periodic force generated during the stamping operation of the press is close to or equal to the resonance frequency of the press, the press will produce a resonance phenomenon. The resonance phenomenon is extremely likely to cause structural fatigue and connection loosening of each component of the press, affecting the processing accuracy and operation safety of the press.

[0004] In the prior art, the vibration isolation method for a press generally includes arranging vibration isolators vertically at the bottom of the press to isolate broadband vibration caused by impact. However, traditional vibration isolators composed of springs and viscous dampers generally start to produce vibration isolation effects in the frequency region greater than times the resonance frequency of the press. Therefore, it is only effective for isolating high-frequency vibration components, and it cannot effectively isolate low-frequency vibration and resonance induced by impact, nor can it effectively suppress the vibration generated by the press in the horizontal direction. In addition, the vibration isolation method for a press also includes arranging a tuned mass damper on the press body. However, the general method of using a conventional tuned mass damper is to set the vibration control efficiency of the tuned mass damper to a fixed parameter, that is, it cannot flexibly and accurately adjust the vibration control efficiency according to the actual vibration situation of the press, resulting in a poor resonance suppression effect of the press. For example, when the vibration control efficiency of the tuned mass damper is set weakly, the resonance of the press cannot be fully suppressed. When the vibration control efficiency of the tuned mass damper is set too strongly, it will affect the normal stamping operation force release of the press. Summary of the Invention

[0005] The present invention provides a method and system for suppressing low-frequency resonance of a press to solve the technical problem that a conventional press cannot achieve the functions of multi-directional resonance frequency detection and resonance frequency suppression during the stamping operation in the prior art.

[0006] To solve the above problems, the technical solution of the present invention is: A method for suppressing low-frequency resonance of a press includes the following steps: S1: Obtain the multi-order modal vibration modes and corresponding vibration frequencies of the press under theoretical conditions through finite element analysis and vibration testing; S2: Based on the multi-order modal vibration modes and corresponding vibration frequency data of the press, determine the vibration frequency ranges at different component positions of the press entity. Configure at least one set of triaxial acceleration sensors and resonance suppression units at the positions of the comprehensive vibration frequency peaks in the press entity. The resonance suppression unit includes non-linear dynamic vibration absorbers distributed along the x-axis, y-axis, and z-axis respectively; S3: The triaxial acceleration sensors periodically collect the vibration signals of the press, calculate and obtain the resonance frequencies of the press in the three axial directions. The non-linear dynamic vibration absorbers distributed along the x-axis, y-axis, and z-axis adjust their vibration control efficiency correspondingly based on the real-time resonance frequencies of the press in the three axial directions, and suppress the low-frequency resonance frequencies of the press in the vertical and horizontal directions within a preset range.

[0007] Preferably, in S1, the multi-order modal vibration modes and corresponding vibration frequencies of the press are obtained by using finite element analysis and vibration simulation tests, which specifically include the following steps: S11: Establish a three-dimensional model of the press in the simulation software, simplify the main structure of the three-dimensional model of the press, and eliminate the unnecessary structural features in the three-dimensional model of the press; S12: Divide the three-dimensional model of the press into a number of tetrahedral mesh elements with a preset accuracy; S13: Define the material properties of different components of the three-dimensional model of the press in the simulation software, set the boundary conditions of the three-dimensional model of the press, and input the simulated load conditions applied to the three-dimensional model of the press; S14: Simulate and calculate the multi-order modal vibration modes and corresponding vibration frequency data of the three-dimensional model of the press under different vibration simulation test conditions.

[0008] Preferably, in S3, the triaxial acceleration sensors collect the vibration signals of the press, calculate and obtain the resonance frequencies of the press in the three axial directions, which specifically include the following steps: S31: The main controller obtains the production beat parameters of the press, and evenly divides the single stamping action time of the press into a number of minimum resonance suppression periods; S32: The triaxial acceleration sensors use the minimum resonance suppression period as the sampling period, collect the vibration signals of the press and transmit them to the main controller. The main controller uses the minimum resonance suppression period as the processing window, and sequentially performs fast Fourier transform processing on the vibration signals of the press to obtain the resonance frequency spectrograms of the press within a number of minimum resonance suppression periods respectively; S33: The main controller calculates the amplitude of the frequency components of each resonance frequency spectrogram respectively, traverses all the amplitude values in the resonance frequency spectrogram, and sets the maximum amplitude value in each resonance frequency spectrogram as the resonance frequency of the current minimum resonance suppression period.

[0009] Preferably, in S32, the triaxial acceleration sensor collects the vibration signal of the press, and the following steps are further included: S321: The triaxial acceleration sensor collects the acceleration data of the press in the x-axis, y-axis, and z-axis directions to form an acceleration sample set and transmits it to the main controller. The main controller filters the vibration signal of the press through a low-pass filter, a high-pass filter, a band-pass filter, or a band-stop filter, and suppresses the noise of the vibration signal of the press through adaptive filtering, wavelet transform, or spectral subtraction to obtain the preprocessed vibration signal of the press.

[0010] Preferably, the non-linear dynamic vibration absorber uses a disc spring to provide non-linear stiffness characteristics, and a mass block for absorbing resonance energy is provided in the non-linear dynamic vibration absorber; In S3, the non-linear dynamic vibration absorbers distributed along the x-axis, y-axis, and z-axis adjust their vibration control efficiency corresponding to the real-time resonance frequencies of the press in the three-axis directions, specifically including the following steps: S34: In any minimum resonance suppression period, according to the resonance frequencies of the press in the three-axis directions, calculate the suppression demand stiffness of the press in the three-axis directions that matches the corresponding resonance frequencies respectively. The calculation method of the suppression demand stiffness is: where k req is the suppression demand stiffness, m is the mass of the mass block of the non-linear dynamic vibration absorber, and f dom is the resonance frequency of the press in a single-axis direction; S35: The calculation method of the stiffness of the disc spring of the non-linear dynamic vibration absorber is: where k z is the stiffness of the disc spring of the non-linear dynamic vibration absorber, E is the elastic modulus of the disc spring of the non-linear dynamic vibration absorber, t is the thickness of the disc spring of the non-linear dynamic vibration absorber, K1 is the geometric coefficient of the disc spring of the non-linear dynamic vibration absorber, and D is the coil diameter of the disc spring of the non-linear dynamic vibration absorber; S36: Establish a pre-compression amount-stiffness relationship model for the disc spring of the non-linear dynamic vibration absorber. The pre-compression amount-stiffness relationship model is expressed as: where k base is the rigid reference parameter, β is the calibration coefficient, is the compression displacement amount of the disc spring of the non-linear dynamic vibration absorber; By adjusting the pre-compression amount of the disc spring of the non-linear dynamic vibration absorber, the stiffness of the disc spring of the non-linear dynamic vibration absorber is approximated to the stiffness required for suppressing the press, so the main controller controls the disc spring compression displacement adjustment command of the non-linear dynamic vibration absorber as follows: 。

[0011] Preferably, during a single stamping operation of the press, the main controller adjusts the vibration control efficiency of the non-linear dynamic vibration absorber in several minimum resonance suppression periods through a PID closed-loop feedback control method. Specifically: it is defined that the low-frequency resonance frequency of the press being within a preset range is the set value of the PID control, the low-frequency resonance frequency of the press after adjustment in each minimum resonance suppression period is the process variable of the PID control, and the difference between the set value and the process variable of the press after adjustment in each minimum resonance suppression period is the error of the PID control.

[0012] Preferably, a method for suppressing the low-frequency resonance of a press further includes the following steps: S4: There is a resonance frequency alarm limit. When the three-axis acceleration sensor collects the vibration signal of the press and calculates that the resonance frequency of the press in the three-axis direction exceeds the resonance frequency alarm limit, the press stops the stamping operation and outputs an alarm signal.

[0013] Based on the same concept, the present invention also provides a low-frequency resonance suppression system for a press, which is used to execute the low-frequency resonance suppression method for a press as described in any one of the above, including: A press, the press includes a fuselage, a stamping slider assembly and a stamping platform; A three-axis acceleration sensor, the three-axis acceleration sensor is used to measure the vibration signals of the press in the x-axis, y-axis and z-axis directions; A resonance suppression unit, the resonance suppression unit includes non-linear dynamic vibration absorbers distributed along the x-axis, y-axis and z-axis respectively, and the resonance suppression unit is used to suppress the low-frequency resonance of the press in the x-axis, y-axis and z-axis directions; Four groups of the three-axis acceleration sensors and the resonance suppression unit are respectively arranged at the four corner positions on the top of the crossbeam of the fuselage.

[0014] Preferably, the non-linear dynamic vibration absorber includes a mass block, a slide rail, a non-linear disc spring and a ball screw servo motor; The slide rail is arranged to extend along the height direction of the non-linear dynamic vibration absorber. The mass block is slidably connected to the slide rail. The bottom of the mass block is provided with the non-linear disc spring that extends along the height direction of the non-linear dynamic vibration absorber. The first end of the non-linear disc spring abuts against the mass block. The ball screw servo motor is configured to drive the mass block to move, and the mass block compresses the non-linear disc spring to cause the non-linear disc spring to generate a compression displacement.

[0015] Preferably, four groups of vertically arranged vibration isolators are respectively provided at the four corner positions of the bottom of the fuselage. The vibration isolators are used to isolate the high-frequency vibration formed during the stamping operation of the press. The non-linear dynamic vibration absorber further includes a damper. The inside of the damper is provided with a silicon-based damping liquid. The second end of the non-linear disc spring abuts against the movable end face of the damper. The damper is configured such that when the ball screw servo motor drives the mass block to move, the mass block compresses the non-linear disc spring, and the non-linear disc spring compresses the silicon-based damping liquid inside the damper to adjust the vibration control efficiency of the non-linear dynamic vibration absorber.

[0016] Due to the adoption of the above technical solutions, the present invention has the following advantages and positive effects compared with the prior art: The present invention provides a method and system for suppressing low-frequency resonance of a press. By finite element analysis and vibration simulation tests, it is determined that the top cross beam of the press fuselage is the position of the peak value of the comprehensive vibration frequency. Therefore, triaxial acceleration sensors and resonance suppression units are respectively arranged at the four corner positions of the top of the cross beam of the press. The resonance suppression unit includes non-linear dynamic vibration absorbers distributed along the x-axis, y-axis, and z-axis respectively. During the stamping operation of the press, the triaxial acceleration sensors collect the vibration signals of the press, and the main controller calculates and obtains the resonance frequencies of the press in the triaxial directions. The non-linear dynamic vibration absorbers distributed along the x-axis, y-axis, and z-axis adjust their vibration control efficiencies corresponding to the real-time resonance frequencies of the press in the triaxial directions, thereby suppressing the low-frequency resonance frequencies of the press in the vertical and horizontal directions within a preset range, fully improving the stamping accuracy, stability, and production efficiency of the press, and avoiding unnecessary energy consumption. It has important theoretical and practical application values for promoting the research and manufacture of high-precision, low-vibration-noise, and environmentally friendly large stamping equipment. Description of the Drawings

[0017] Figure 1 A flowchart of a method for suppressing low-frequency resonance of a press provided by the present invention; Figure 2 A structural schematic diagram of the press provided by the present invention; Figure 3 A structural schematic diagram of the non-linear dynamic vibration absorber provided by the present invention; Figure 4 The comparison diagram of the resonance frequency of the press provided by the present invention near the 2 Hz frequency band in one direction; Figure 5 The comparison diagram of the resonance frequency of the press provided by the present invention near the 6 Hz frequency band in one direction.

[0018] Description of reference numerals: 1: Press; 11: Cross beam; 12: Stamping slider; 13: Column; 14: Stamping platform; 15: Base; 16: Vibration isolator; 2: Nonlinear dynamic vibration absorber; 21: Mass block; 22: Ball screw servo motor; 23: Disc spring; 24: Slide rail; 25: Damper. Detailed implementation manners

[0019] The following further details a low-frequency resonance suppression method and system for a press proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will be clearer according to the following description and the claims.

[0020] First embodiment Refer to Figures 1 - 3 , this embodiment provides a low-frequency resonance suppression method for a press, which is used to realize the resonance dynamic suppression function of the press 1 in the vertical direction and the horizontal direction, and includes the following steps: S1: Through finite element analysis and vibration simulation tests, obtain the multi-order modal vibration modes and corresponding vibration frequencies of the press 1 under theoretical conditions.

[0021] S2: Based on the multi-order modal vibration modes and corresponding vibration frequency data of the press 1, determine the vibration frequency range at different component positions of the press 1 entity, select the position of the comprehensive vibration frequency peak in the press 1 entity, and configure at least one set of triaxial acceleration sensors and one set of resonance suppression units at the position of the comprehensive vibration frequency peak in the press 1 entity. The resonance suppression unit includes nonlinear dynamic vibration absorbers 2 distributed along the x-axis, y-axis, and z-axis respectively.

[0022] In this embodiment, through the simulation results, the top of the press 1 fuselage (cross beam 11) is selected as the position of the comprehensive vibration frequency peak, and triaxial acceleration sensors are respectively arranged at the four corners of the top of the cross beam 11 of the press 1, and nonlinear dynamic vibration absorbers 2 distributed along the x-axis, y-axis, and z-axis. It is assumed that for the press 1 facing the observer frontally, the x-axis refers to the horizontal transverse direction of the press 1, the y-axis refers to the horizontal longitudinal direction of the press 1, and the z-axis refers to the vertical direction of the press 1.

[0023] Among them, the non-linear dynamic vibration absorber 2, also known as the non-linear energy sink, consists of a non-linear equivalent spring-mass system installed on the vibrating machine. Its core mechanism does not rely on matching a fixed resonance frequency, but realizes transient resonance capture and energy absorption, that is, realizes wide-band vibration absorption through non-linear target energy transfer and adaptive frequency response. Therefore, it has better robustness to the resonance frequency change adaptation of the press 1 and has the ability of wide-band energy dissipation.

[0024] S3: The triaxial acceleration sensor periodically collects the vibration signals of the press 1, calculates and obtains the resonance frequencies of the press 1 in the triaxial directions. The non-linear dynamic vibration absorbers 2 distributed along the x-axis, y-axis and z-axis adjust their vibration control effectiveness correspondingly based on the real-time resonance frequencies of the press 1 in the triaxial directions, so as to suppress the low-frequency resonance frequencies of the press 1 in the vertical and horizontal directions within a preset range.

[0025] In summary, this embodiment provides a method for suppressing low-frequency resonance of a press. At the peak position of the comprehensive vibration frequency of the press 1, the triaxial acceleration sensor detects the vibration frequencies of the press 1 in the triaxial directions. When the vibration frequency exceeds the preset threshold, the non-linear dynamic vibration absorber 2 in the corresponding direction dynamically adjusts its vibration control effectiveness, suppresses the resonance frequency of the press 1 in this direction within the preset range, and cooperates with four groups of triaxial acceleration sensors and resonance suppression units to ensure effective suppression of the vertical and horizontal low-frequency resonances of the press 1 caused by stamping work excitation, and improves the processing accuracy and equipment stability of the press 1 during the stamping operation.

[0026] Next, the specific implementation steps and functions of a method for suppressing low-frequency resonance of a press provided by this embodiment will be further described in detail: Preferably, in one embodiment, in S1, the multi-order modal vibration modes and corresponding vibration frequencies of the press are obtained by finite element analysis and vibration simulation tests, which specifically include the following steps: S11: Establish a three-dimensional model of the press 1 in a simulation software (such as ANSYS, ABAQUS, NASTRAN, etc.), and simplify the main structure of the three-dimensional model of the press 1 to eliminate unnecessary structural features in the three-dimensional model of the press 1, such as deleting the process fillets and chamfers of all components, and appropriately repairing the three-dimensional model by filling, merging surfaces, etc., so as to improve the simulation calculation efficiency and analyticality of the subsequent three-dimensional model of the press 1.

[0027] S12: Divide the 3D model of the press 1 into a number of tetrahedral mesh elements with a preset precision. Each tetrahedral mesh element has nodes, and adjacent tetrahedral mesh elements are connected by nodes. In this embodiment, the size of the tetrahedral mesh element is controlled within 30mm * 30mm * 30mm, and the refined tetrahedral mesh elements are used to ensure the accuracy and convergence of the calculation results.

[0028] S13: Define the material properties of different components of the 3D model of the press 1 in the simulation software, such as elastic modulus, Poisson's ratio, density, etc., to ensure that different components in the 3D model of the press 1 can accurately and realistically reflect the physical properties of the actual materials.

[0029] Set the boundary conditions of the 3D model of the press 1, such as the fixed points and symmetry planes of the press 1.

[0030] And according to the actual working conditions of the press 1, input the simulated load conditions applied to the 3D model of the press 1 in the simulation software, such as the applied forces, pressures, temperatures and other external loads borne by each component in the 3D model of the press 1 during the stamping process of the stamping machine.

[0031] S14: Simulate and calculate the multi-order modal vibration modes and corresponding vibration frequency data of the 3D model of the press 1 under different vibration simulation test conditions.

[0032] By analyzing the multi-order modal vibration modes and corresponding vibration frequency data of the press 1, the vibration frequency range at different component positions of the press 1 entity can be obtained. In this embodiment, the peak value of the comprehensive vibration frequency in the three-axis direction measured at the position of the crossbeam 11 of the press 1 is the highest. Therefore, the crossbeam 11 of the press 1 is selected as the layout position of the three-axis acceleration sensor and the resonance suppression unit. When the resonance of the crossbeam 11 position of the press 1 is suppressed within the preset range, it means that the resonance suppression of the entire press 1 is within the preset range.

[0033] Preferably, in one embodiment, in S3, the three-axis acceleration sensor collects the vibration signal of the press 1, and calculates and obtains the resonance frequency of the press 1 in the three-axis direction, which specifically includes the following steps: S31: The main controller obtains the production beat parameters of the press 1, such as the number of stamping times per minute, and further evenly divides the single stamping action time of the press 1 into a number of minimum resonance suppression periods.

[0034] S32: The triaxial acceleration sensor uses the minimum resonance suppression period as the sampling period to collect the vibration signal of the press 1 and transmit it to the main controller. In this embodiment, the main controller is responsible for digitally processing the vibration signal, as well as controlling the operating parameters of the press 1 and the vibration control efficiency of the nonlinear dynamic vibration absorber 2. The main controller uses the minimum resonance suppression period as the processing window and sequentially performs fast Fourier transform processing (FFT) on the vibration signal of the press 1, converting the acceleration signal in the time domain into a frequency-domain representation, and respectively obtaining the resonance spectrograms of the press 1 within several minimum resonance suppression periods. The resonance spectrogram can reflect the change in the resonance frequency of the press 1 within a single minimum resonance suppression period.

[0035] S33: The main controller calculates the amplitude of each frequency component of each resonance spectrogram respectively, traverses all the amplitude values in the resonance spectrogram, sets the maximum amplitude value in each resonance spectrogram as the resonance frequency of the current minimum resonance suppression period, and within the current minimum resonance suppression period, the nonlinear dynamic vibration absorber 2 adjusts its vibration control efficiency based on the resonance frequency.

[0036] It should be noted that in this embodiment, any set of triaxial acceleration sensors and the nonlinear dynamic vibration absorber 2 operate independently. For example, if the triaxial acceleration sensor at the first position of the crossbeam 11 of the press 1 detects resonance in the x-axis direction at the first position of the press 1, but no resonance is detected in the y-axis and z-axis, then the nonlinear dynamic vibration absorber 2 arranged along the x-axis at the first position of the crossbeam 11 of the press 1 adjusts its vibration control efficiency, while the nonlinear dynamic vibration absorbers 2 arranged along the y-axis and z-axis do not participate in the adjustment of the vibration control efficiency.

[0037] In other embodiments, the number of triaxial acceleration sensors and resonance suppression units is not limited to four groups. By arranging several groups of triaxial acceleration sensors and resonance suppression units at different positions of the press 1, the vibration frequencies at different positions of the press 1 can be detected independently, thereby improving the detection accuracy of abnormal vibrations when a single component of the press 1 detaches from the press 1 due to vibration. The arrangement of the four groups of triaxial acceleration sensors and resonance suppression units is for the purpose of achieving the optimal balance between cost and resonance suppression effect.

[0038] Preferably, in one embodiment, when the triaxial acceleration sensor in S32 collects the vibration signal of the press 1, the following steps are further included: S321: The triaxial acceleration sensor collects the acceleration data of the press 1 in the x-axis, y-axis, and z-axis directions to form an acceleration sample set and transmits it to the main controller. The main controller filters the vibration signal of the press 1 through a low-pass filter, a high-pass filter, a band-pass filter, or a band-stop filter, and suppresses the noise of the vibration signal of the press 1 through adaptive filtering, wavelet transform, or spectral subtraction, so that the vibration signal is removed from noise interference, thereby obtaining the preprocessed vibration signal of the press 1.

[0039] Preferably, in an embodiment, the nonlinear dynamic vibration absorber 2 includes a mass block 21, a slide rail 24, a nonlinear disc spring 23, and a ball screw servo motor 22. The slide rail 24 extends along the height direction of the nonlinear dynamic vibration absorber 2 (for example, for the nonlinear dynamic vibration absorber 2 arranged along the x-axis direction, its slide rail 24 also extends along the x-axis direction). The mass block 21 is slidably connected to the slide rail 24. A nonlinear disc spring 23 extending along the height direction of the nonlinear dynamic vibration absorber 2 is provided at the bottom of the mass block 21. The first end of the nonlinear disc spring 23 abuts against the mass block 21. The ball screw servo motor 22 is configured to drive the mass block 21 to move, and the mass block 21 compresses the nonlinear disc spring 23 to cause the nonlinear disc spring 23 to generate a compression displacement.

[0040] Among them, the nonlinear dynamic vibration absorber 2 uses the disc spring 23 to provide a nonlinear stiffness characteristic and uses the mass block 21 to absorb resonance energy. That is, when it is detected that the press 1 has resonance enhancement, the ball screw servo motor 22 can adjust the disc spring 23 to stretch, so that the resonance energy absorption performance of the mass block 21 is correspondingly enhanced. On the contrary, when it is detected that the press 1 has resonance weakening, the ball screw servo motor 22 can adjust the disc spring 23 to contract, so that the resonance energy absorption performance of the mass block 21 is correspondingly weakened.

[0041] In S3, the nonlinear dynamic vibration absorbers 2 distributed along the x-axis, y-axis, and z-axis adjust their vibration control efficiency based on the real-time resonance frequency of the press 1 in the three-axis direction, specifically including the following steps: S34: In any minimum resonance suppression period, according to the resonance frequencies of the press 1 in the three-axis directions, calculate the suppression demand stiffness (that is, the external force stiffness required to suppress the resonance of the press 1 and adjust it to the preset range) matching the corresponding resonance frequencies in the three-axis directions of the press 1. The calculation method of the suppression demand stiffness is: Among them, k req is the suppression demand stiffness, m is the mass of the mass block 21 of the nonlinear dynamic vibration absorber 2, and f dom is the resonance frequency of the press 1 in the single-axis direction.

[0042] S35: For the structure of the non - linear dynamic vibration absorber 2 provided in this embodiment, the calculation method of the stiffness of the disc spring 23 of the non - linear dynamic vibration absorber 2 is as follows: where k z is the stiffness of the disc spring 23 of the non - linear dynamic vibration absorber 2, E is the elastic modulus of the disc spring 23 of the non - linear dynamic vibration absorber 2, t is the thickness of the disc spring 23 of the non - linear dynamic vibration absorber 2, K1 is the geometric coefficient of the disc spring 23 of the non - linear dynamic vibration absorber 2 (related to the inner diameter, outer diameter, and thickness ratio, determined by empirical formula or experiment), and D is the coil diameter of the disc spring 23 of the non - linear dynamic vibration absorber 2.

[0043] S36: Establish a pre - compression amount - stiffness relationship model for the disc spring 23 of the non - linear dynamic vibration absorber 2, and the pre - compression amount - stiffness relationship model is expressed as: where k base is the rigid reference parameter (the initial stiffness of the disc spring 23 under no pre - compression or reference pre - compression amount), β is the calibration coefficient (obtained from the stiffness test curve of the disc spring 23), is the compression displacement of the disc spring 23 of the non - linear dynamic vibration absorber 2.

[0044] By adjusting the pre - compression amount of the disc spring 23 of the non - linear dynamic vibration absorber 2, the stiffness of the disc spring 23 of the non - linear dynamic vibration absorber 2 is approximated to the suppression - required stiffness of the press 1, that is, the non - linear dynamic vibration absorber 2 provides the suppression - required stiffness. Therefore, the specific command for the main controller to control the compression displacement of the disc spring 23 of the non - linear dynamic vibration absorber 2 is: Thus, the dynamic suppression function of the non - linear dynamic vibration absorber 2 for the resonance of the press 1 is realized.

[0045] Preferably, in one embodiment, during a single stamping operation of the press 1, the main controller adjusts the vibration control efficiency of the non - linear dynamic vibration absorber 2 in several minimum resonance suppression periods through the PID closed - loop feedback control method. Specifically: Define that the low - frequency resonance frequency of the press 1 within a preset range is the set value of the PID control, the low - frequency resonance frequency of the press 1 after adjustment in each minimum resonance suppression period is the process variable of the PID control, and the difference between the set value and the process variable of the press 1 after adjustment in each minimum resonance suppression period is the error of the PID control.

[0046] With the aid of the PID control method, the dynamic response speed and stability of the non - linear dynamic vibration absorber 2 can be improved, ensuring effective suppression and precise adjustment of the resonance of the press 1.

[0047] Preferably, in one embodiment, the method for suppressing low-frequency resonance of the press 1 further includes the following steps: S4: A resonance frequency alarm limit is set. When the triaxial acceleration sensor collects the vibration signal of the press 1 and calculates that the resonance frequency of the press 1 in the triaxial direction exceeds the resonance frequency alarm limit, it indicates that the resonance of the press 1 is too high and has exceeded the safe and controllable range. The press 1 stops the stamping operation and outputs an alarm signal.

[0048] See Figures 4 - 5 , which is a comparison chart of resonance experimental frequencies near the 2 Hz frequency band and the 6 Hz frequency band in one direction after the triaxial acceleration sensor and the resonance suppression unit are equipped on the press 1 in this embodiment. It can be seen from the figure that the resonance situation of the press 1 in its resonance area is significantly suppressed.

[0049] Second Embodiment Based on the same concept, the present invention also provides a low-frequency resonance suppression system for a press, which is used to execute the low-frequency resonance suppression method of the press described in the first embodiment, and includes a press 1, a triaxial acceleration sensor, and a resonance suppression unit.

[0050] The main structure of the press 1 includes a fuselage, a stamping slider assembly, and a stamping platform 14. The top of the fuselage is a crossbeam 11 component, the side is provided with a column 13 component for support, and the bottom is a base 15. The stamping slider assembly and the stamping platform 14 are arranged in the internal cavity space of the fuselage. The stamping slider assembly is movably arranged in the space above the stamping platform 14. The stamping slider assembly includes a power system and a stamping slider 12. During the stamping operation of the press, the stamping slider 12 presses down vertically onto the stamping platform 14 to apply pressure to the workpiece on the stamping platform 14.

[0051] The triaxial acceleration sensor is used to measure the acceleration data of the press 1 in the x-axis, y-axis, and z-axis directions, which is the vibration signal of the press 1 in the x-axis, y-axis, and z-axis directions in this embodiment.

[0052] The resonance suppression unit includes non-linear dynamic vibration absorbers 2 distributed along the x-axis, y-axis, and z-axis respectively. The resonance suppression unit is used to suppress the low-frequency resonance of the press 1 in the x-axis, y-axis, and z-axis directions.

[0053] In this embodiment, there are four sets of both the triaxial acceleration sensors and the resonance suppression units, which are respectively arranged at the four corner positions on the top of the cross beam 11 of the fuselage. Among them, for the press 1 with the front facing the observer, taking the first position at a certain corner on the top of the cross beam 11 of the fuselage as an example, the x-axis nonlinear dynamic vibration absorber 2 is vertically arranged on the lateral side wall at the first position on the top of the cross beam 11 of the fuselage, the y-axis nonlinear dynamic vibration absorber 2 is vertically arranged on the longitudinal side wall at the first position on the top of the cross beam 11 of the fuselage, and the z-axis nonlinear dynamic vibration absorber 2 is vertically arranged on the vertical top surface at the first position on the top of the cross beam 11 of the fuselage.

[0054] It is worth noting that in this embodiment, the triaxial acceleration sensor and the resonance suppression unit at each corner position on the top of the cross beam 11 of the fuselage form an integral structure, that is, the resonance suppression unit only makes corresponding adjustments to the vibration control efficiency according to the vibration signals measured by the corresponding triaxial acceleration sensor.

[0055] Preferably, in one embodiment, the nonlinear dynamic vibration absorber 2 internally includes a mass block 21, a slide rail 24, a nonlinear disc spring 23, and a ball screw servo motor 22.

[0056] The slide rail 24 extends along the height direction of the nonlinear dynamic vibration absorber 2. The mass block 21 is slidably connected to the slide rail 24 and can slide along the extension direction of the slide rail 24, that is, the height of the mass block 21 inside the nonlinear dynamic vibration absorber 2 can change. A nonlinear disc spring 23 extending along the height direction of the nonlinear dynamic vibration absorber 2 is provided at the bottom of the mass block 21. There are two groups of nonlinear disc springs 23, which are symmetrically arranged on both sides of the bottom of the mass block 21. The first end (top end) of the nonlinear disc spring 23 abuts against the bottom surface of the mass block 21. The ball screw servo motor 22 is configured to drive the mass block 21 to move towards or away from the nonlinear disc spring 23. The mass block 21 compresses the nonlinear disc spring 23, causing the nonlinear disc spring 23 to generate a compression displacement (including the stretching movement of the nonlinear disc spring 23 when the mass block 21 moves upward and the contraction movement of the nonlinear disc spring 23 when the mass block 21 moves downward). In the nonlinear dynamic vibration absorber 2, when the ball screw servo motor 22 adjusts the disc spring 23 to stretch, the resonance energy absorption performance of the mass block 21 is enhanced. On the contrary, when the ball screw servo motor 22 adjusts the disc spring 23 to contract, the resonance energy absorption performance of the mass block 21 is weakened. In this embodiment, by controlling the compression displacement amount of the mass block 21 and the nonlinear disc spring 23, the dynamic adjustment of the vibration control efficiency of the nonlinear dynamic vibration absorber 2 can be realized, fully adapting to the resonance suppression requirements of the press 1 at different times, and adjusting the nonlinear stiffness and damping of the vibration absorber according to the vibration characteristics of the press 1 to match the vibration absorption frequency range.

[0057] Preferably, in one embodiment, four sets of vertically arranged vibration isolators 16 are respectively provided at the four corner positions of the bottom of the base 15 of the body of the press 1. The vibration isolators 16 are used to isolate the high-frequency vibration generated by the press 1 during stamping operations. By isolating and eliminating the high-frequency vibration generated by the press 1 during stamping operations, the detection accuracy of the triaxial acceleration sensor for only low-frequency resonance can be improved.

[0058] Further, the non-linear dynamic vibration absorber 2 further includes a damper 25. The damper 25 is filled with a silicon-based damping fluid. The second end (bottom end) of the non-linear disc spring 23 abuts against the movable end face of the damper 25, applying pressure to the movable end face of the damper 25, which can change the viscosity of the silicon-based damping fluid inside the damper 25. That is, when the silicon-based damping fluid is compressed, its viscosity increases, and conversely, when the silicon-based damping fluid expands, its viscosity decreases.

[0059] In this embodiment, the damper 25 is configured to drive the mass block 21 to move through the ball screw servo motor 22. The mass block 21 compresses the non-linear disc spring 23, causing the non-linear disc spring 23 to further compress the silicon-based damping fluid inside the damper 25, and adjusting the vibration control efficiency of the non-linear dynamic vibration absorber 2. Specifically, when the ball screw servo motor 22 adjusts the disc spring 23 to expand, the pressure on the silicon-based damping fluid inside the damper 25 weakens, the viscosity of the silicon-based damping fluid weakens, and the vibration absorption effect of the damper 25 increases. Cooperating with the non-linear disc spring 23 and the mass block 21, the resonance energy absorption performance of the mass block 21 is improved. Conversely, when the ball screw servo motor 22 adjusts the disc spring 23 to contract, the pressure on the silicon-based damping fluid inside the damper 25 increases, the viscosity of the silicon-based damping fluid increases, and the vibration absorption effect of the damper 25 weakens. Cooperating with the non-linear disc spring 23 and the mass block 21, the resonance energy absorption performance of the mass block 21 is reduced. Through the cooperative operation of the non-linear disc spring 23 and the damper 25, the release efficiency of the vibration control efficiency of the non-linear dynamic vibration absorber 2 can be improved.

[0060] In summary, the present invention provides a method and system for suppressing low-frequency resonance of a press. By means of finite element analysis and vibration simulation tests, it is determined that the top cross beam 11 of the press body of the press 1 is the position of the peak value of the comprehensive vibration frequency. Therefore, triaxial acceleration sensors and resonance suppression units are respectively arranged at the four corner positions on the top of the cross beam 11 of the press 1. The resonance suppression unit includes non-linear dynamic vibration absorbers 2 distributed along the x-axis, y-axis and z-axis respectively. During the stamping operation of the press 1, the triaxial acceleration sensors collect the vibration signals in the triaxial directions of the press 1, and the main controller calculates and obtains the resonance frequencies of the press 1 in the triaxial directions. The non-linear dynamic vibration absorbers 2 distributed along the x-axis, y-axis and z-axis adjust their vibration control efficiency correspondingly based on the real-time resonance frequencies of the press 1 in the triaxial directions, thereby suppressing the low-frequency resonance frequencies of the press 1 in the vertical and horizontal directions within a preset range, fully improving the stamping accuracy, stability and production efficiency of the press 1, and avoiding unnecessary energy consumption, which has important theoretical and practical application values for promoting the research and manufacture of large-scale stamping equipment with high precision, low vibration noise and environmental friendliness.

[0061] The above has described in detail the embodiments of the present invention in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, provided that these changes fall within the scope of the claims of the present invention and their equivalent technologies, they still fall within the protection scope of the present invention.

Claims

1. A method for suppressing low-frequency resonance of a press, characterized in that, The method includes the following steps: S1: Obtain the multi-order modal vibration modes and corresponding vibration frequencies of the press under theoretical conditions through finite element analysis and vibration testing; S2: Based on the multi-order modal vibration modes and corresponding vibration frequency data of the press, determine the vibration frequency ranges at different component positions of the press entity, and configure at least one set of triaxial acceleration sensors and resonance suppression units at the positions of the comprehensive vibration frequency peaks in the press entity. The resonance suppression unit includes non-linear dynamic vibration absorbers distributed along the x-axis, y-axis, and z-axis respectively; S3: The triaxial acceleration sensors periodically collect the vibration signals of the press, calculate and obtain the resonance frequencies of the press in the triaxial directions. The non-linear dynamic vibration absorbers distributed along the x-axis, y-axis, and z-axis adjust their vibration control effectiveness correspondingly based on the real-time resonance frequencies of the press in the triaxial directions, and suppress the low-frequency resonance frequencies of the press in the vertical and horizontal directions within a preset range.

2. The method for suppressing low-frequency resonance of a press according to claim 1, characterized in that In S1, the multi-order modal vibration modes and corresponding vibration frequencies of the press are obtained by using finite element analysis and vibration simulation testing, which specifically includes the following steps: S11: Establish a three-dimensional model of the press in the simulation software, simplify the main structure of the three-dimensional model of the press, delete the process fillets and chamfers of all components in the three-dimensional model of the press, and repair the three-dimensional model of the press by filling and merging surfaces; S12: Divide the three-dimensional model of the press into a number of tetrahedral mesh elements with a preset accuracy; S13: Define the material properties of different components of the three-dimensional model of the press in the simulation software, set the boundary conditions of the three-dimensional model of the press, and input the simulated load conditions applied to the three-dimensional model of the press; S14: Perform simulation calculations on the multi-order modal vibration modes and corresponding vibration frequency data of the three-dimensional model of the press under different vibration simulation test conditions.

3. The method for suppressing low-frequency resonance of a press according to claim 1, wherein In S3, the triaxial acceleration sensors collect the vibration signals of the press, calculate and obtain the resonance frequencies of the press in the triaxial directions, which specifically includes the following steps: S31: The main controller obtains the production beat parameters of the press, and evenly divides the single stamping action time of the press into a number of minimum resonance suppression periods; S32: The triaxial acceleration sensors use the minimum resonance suppression period as the sampling period to collect the vibration signals of the press and transmit them to the main controller. The main controller uses the minimum resonance suppression period as the processing window, and sequentially performs fast Fourier transform processing on the vibration signals of the press to obtain the resonance spectrograms of the press within a number of minimum resonance suppression periods respectively; S33: The main controller calculates the amplitude of the frequency components of each resonance spectrogram respectively, traverses all the amplitude values in the resonance spectrogram, and sets the maximum amplitude value in each resonance spectrogram as the resonance frequency of the current minimum resonance suppression period.

4. The method for suppressing low-frequency resonance of a press according to claim 3, characterized in that, In S32, when the triaxial acceleration sensors collect the vibration signals of the press, the following steps are further included: S321: The triaxial acceleration sensor collects the acceleration data of the press in the x-axis, y-axis, and z-axis directions to form an acceleration sample set and transmits it to the main controller. The main controller filters the vibration signal of the press through a low-pass filter, a high-pass filter, a band-pass filter, or a band-stop filter, and suppresses the noise of the vibration signal of the press through adaptive filtering, wavelet transform, or spectral subtraction to obtain the preprocessed vibration signal of the press.

5. The method for suppressing low-frequency resonance of a press according to claim 3, characterized in that, The non-linear dynamic vibration absorber uses a disc spring to provide non-linear stiffness characteristics, and a mass block for absorbing resonance energy is provided in the non-linear dynamic vibration absorber; In S3, the non-linear dynamic vibration absorbers distributed along the x-axis, y-axis, and z-axis adjust their vibration control efficiency corresponding to the real-time resonance frequencies of the press in the three-axis directions, specifically including the following steps: S34: In any minimum resonance suppression period, according to the resonance frequencies of the press in the three-axis directions, calculate the suppression demand stiffnesses of the press in the three-axis directions that match the corresponding resonance frequencies respectively. The calculation method of the suppression demand stiffness is: where k req is for suppressing the demand stiffness, m is the mass of the mass block of the non-linear dynamic vibration absorber, and f dom is the resonance frequency of the press in the uniaxial direction; S35: The calculation method of the stiffness of the disc spring of the non-linear dynamic vibration absorber is: where k z is the stiffness of the disc spring of the non-linear dynamic vibration absorber, E is the elastic modulus of the disc spring of the non-linear dynamic vibration absorber, t is the thickness of the disc spring of the non-linear dynamic vibration absorber, K1 is the geometric coefficient of the disc spring of the non-linear dynamic vibration absorber, and D is the coil diameter of the disc spring of the non-linear dynamic vibration absorber; S36: Establish a pre-compression amount-stiffness relationship model of the disc spring of the non-linear dynamic vibration absorber, and the pre-compression amount-stiffness relationship model is expressed as: Among them, k base is a rigid reference parameter, β is a calibration coefficient, is the compression displacement of the disc spring of the non-linear dynamic vibration absorber; By adjusting the pre-compression amount of the disc spring of the non-linear dynamic vibration absorber, make the stiffness of the disc spring of the non-linear dynamic vibration absorber approach the suppression demand stiffness of the press. Therefore, the main controller controls the disc spring compression displacement adjustment instruction of the non-linear dynamic vibration absorber as: 。 6. The method for suppressing low-frequency resonance of a press according to claim 5, characterized in that, During a single stamping operation of the press, the main controller adjusts the vibration control efficiency of the non-linear dynamic vibration absorber in several minimum resonance suppression periods through the PID closed-loop feedback control method. Specifically: define that the low-frequency resonance frequency of the press being within a preset range is the set value of the PID control, the low-frequency resonance frequency of the press after adjustment in each minimum resonance suppression period is the process variable of the PID control, and the difference between the set value and the process variable of the press after adjustment in each minimum resonance suppression period is the error of the PID control.

7. The method for suppressing low-frequency resonance of a press according to claim 1, characterized in that It further includes the following steps: S4: There is a resonance frequency alarm limit. When the triaxial acceleration sensor collects the vibration signal of the press and calculates that the resonance frequencies of the press in the three-axis directions exceed the resonance frequency alarm limit, the press stops the stamping operation and outputs an alarm signal.

8. A low-frequency resonance suppression system for a press, characterized in that, For implementing the low-frequency resonance suppression method of the press as described in any one of claims 1-7, it includes: A press, which includes a body, a stamping slider assembly, and a stamping platform; A triaxial acceleration sensor, which is used to measure the vibration signals of the press in the x-axis, y-axis, and z-axis directions; A resonance suppression unit, which includes non-linear dynamic vibration absorbers distributed along the x-axis, y-axis, and z-axis respectively. The resonance suppression unit is used to suppress the low-frequency resonance of the press in the x-axis, y-axis, and z-axis directions. The three-axis acceleration sensors and the resonance suppression units are both provided with four groups, which are respectively arranged at the four corner positions of the top of the cross beam of the fuselage.

9. The press low-frequency resonance suppression system according to claim 8, characterized in that, The non-linear dynamic vibration absorber includes a mass block, a slide rail, a non-linear disc spring and a ball screw servo motor; The slide rail is arranged along the height direction of the non-linear dynamic vibration absorber. The mass block is slidably connected to the slide rail. The bottom of the mass block is provided with the non-linear disc spring arranged along the height direction of the non-linear dynamic vibration absorber. The first end of the non-linear disc spring abuts against the mass block. The ball screw servo motor is configured to drive the mass block to move, and the mass block compresses the non-linear disc spring to cause the non-linear disc spring to generate a compression displacement.

10. The press low-frequency resonance suppression system according to claim 9, characterized in that Four groups of vertically arranged vibration isolators are respectively provided at the four corner positions of the bottom of the fuselage. The vibration isolators are used to isolate the high-frequency vibration formed during the stamping operation of the press; The non-linear dynamic vibration absorber further includes a damper. The damper is internally provided with a silicon-based damping liquid. The second end of the non-linear disc spring abuts against the movable end face of the damper. The damper is configured such that the ball screw servo motor drives the mass block to move, and the mass block compresses the non-linear disc spring, causing the non-linear disc spring to compress the silicon-based damping liquid inside the damper to adjust the vibration control efficiency of the non-linear dynamic vibration absorber.

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