阅读说明：本技术 一种五轴龙门数控加工中心的切削颤振抑制智能控制方法 (Intelligent control method for cutting chatter suppression of five-axis gantry numerical control machining center ) 是由 李爱军 赵小雨 黄敏波 孟祥东 杨宗生 于 2020-06-23 设计创作，主要内容包括：本发明公开了一种五轴龙门数控加工中心的切削颤振抑制智能控制方法,基于机床各进给轴转速信息检测,并根据在线快速傅里叶变换结果,分别计算自适应陷波器中心频率、宽度参数以及深度参数,将该自适应陷波器模块嵌入伺服电机控制电路,对进给伺服电机电流振动频率进行陷波,达到切削振动抑制的目的。从而,减少机床进给轴的在切削加工过程中的切削振动,提高工件加工质量,提高刀具使用寿命,进而提高生产效率。(The invention discloses an intelligent control method for suppressing cutting chatter of a five-axis gantry numerical control machining center, which is characterized in that the method is based on the detection of rotating speed information of each feeding shaft of a machine tool, and respectively calculates the center frequency, width parameters and depth parameters of an adaptive notch filter according to the online fast Fourier transform result, and embeds the adaptive notch filter module into a servo motor control circuit to trap the current vibration frequency of a feeding servo motor so as to achieve the purpose of suppressing cutting chatter. Therefore, cutting vibration of the machine tool feed shaft in the cutting process is reduced, the workpiece processing quality is improved, the service life of the cutter is prolonged, and the production efficiency is improved.)

1. The intelligent control method for suppressing cutting chatter of the five-axis gantry numerical control machining center is characterized in that a self-adaptive wave trap is adopted for suppressing cutting chatter, and the wave trap comprises the following steps: the device comprises a rotating speed detection module, a vibration frequency detection module, a speed loop PI regulation module, a self-adaptive notch filter module and a current loop PI regulation module, wherein the rotating speed detection module is used for being connected with a permanent magnet synchronous motor, detecting the space position information of each feeding shaft in real time, and calculating to obtain a rotating speed signal omega and a rotor feedback speed omega_fdb(ii) a The vibration frequency detection module receives the feedback speed omega of the rotor_fdbWith a reference value omega of the speed of rotation_refPerforming fast Fourier transform on the rotational speed difference value to calculate the vibration frequency; the speed loop PI regulation module is used for giving a given speed reference value omega_refAnd the rotor feedback speed omega output by the rotating speed detection module_fdbPerforming PI regulation on the differenced signal to output a current reference value i_ref(ii) a The adaptive notch filter module is used for receiving a reference current i_refCarrying out self-adaptive notch processing to obtain current i after notch processing^*(ii) a A current loop PI regulating module for receiving the current i after trap processing^*Performing PI regulation to generate a reference voltage U_ref。

2. The intelligent control method for suppressing cutting chatter of the five-axis gantry numerical control machining center according to claim 1, wherein the adaptive notch filter module adopts a double-T-shaped three-parameter notch filter, and a transfer function of the double-T-shaped three-parameter notch filter is as follows:

wherein f is trap central frequency of the trap, unit: hertz (Hz); the width of the trap wave trap, namely the width of two sides when the amplitude is reduced by 3dB by taking the trap wave center frequency as the center, the unit is: hertz (Hz); xi is the notch depth of the wave trap, namely the amplitude ratio of the notch center frequency before and after the notch.

3. The servo motor adaptive notch filter for suppressing vibration of machine tool cutting according to claim 1, wherein the adaptive notch filter module comprises a notch filter center frequency calculating unit, a notch filter width parameter calculating unit, and a notch filter depth parameter calculating unit, wherein:

the central frequency calculation unit of the wave trap is used for calculating the vibration frequency f output by the vibration frequency detection module according to the input₀The center frequency f of the adaptive notch filter is obtained₀；

The width parameter calculation unit of the wave trap sets a signal threshold value H_tIf the frequency point exceeds the threshold, the vibration is considered to be caused, and the frequency point f corresponding to the set threshold is calculated₁、f₂And calculating the center frequency f of the trap₀And taking the difference value of the two threshold frequency points and twice of the larger value of the two threshold frequency points as the width parameter of the wave trap, namely:

＝2*max(f₀-f₁,f₀-f₂)

the depth parameter calculation unit of the wave trap firstly takes the depth parameterAnd calculating the maximum amplitude H after the trap₀And setting a threshold range [ H ]_tl,H_th]Judgment of H₀If the current value is not within the threshold range, introducing a correction parameter:

the corrected depth parameter is ξ_fixLambda ξ and calculating the maximum amplitude after the notch until the amplitude H₀∈[H_tl,H_th]。

4. An intelligent control method for suppressing cutting chatter of a five-axis gantry numerical control machining center, which controls the adaptive notch filter of any one of claims 1-3, and is characterized by comprising the following steps:

step 1, initializing the wave trap, and controlling a main program after the initialization is finished, wherein the main program detects whether an enabling signal of the wave trap is received, and if the enabling signal is not detected, the control program is always in a detection state until the enabling signal of the wave trap is received;

step 2, after an enabling signal of the wave trap is detected, detecting the condition of sampling points, judging whether the number of the sampling points is equal to the number of preset sampling points or not, if the number of the detected sampling points is not the number of the preset sampling points, returning to the initialization state of the wave trap for re-detection until the number of the detected sampling points is consistent with the number of the preset sampling points, and entering step 3;

step 3, performing online calculation on data acquired by sampling points through an FFT online calculation module, and respectively calculating the center frequency, the width parameter and the depth parameter of the self-adaptive notch filter;

step 4, inputting the parameters calculated in the step 3 into a wave trap to complete the updating of the parameters of the wave trap

And 5, embedding the adaptive notch filter into a servo motor control circuit to notch the current vibration frequency of the feeding servo motor.

5. The intelligent control method for suppressing cutting chatter vibration of the five-axis gantry numerical control machining center according to claim 4, wherein speed information of each feeding shaft is collected in real time, and when the harmonic wave of the speed information in a frequency domain exceeds a preset threshold value, an enabling signal of a wave trap is triggered to start an internal wave trapping function of a servo driver so as to trap the resonant frequency of the current of a feeding servo motor.

6. The intelligent control method for suppressing cutting chatter vibration of the five-axis gantry numerical control machining center according to claim 4, wherein the sampling points acquire speed information of each feed axis and sample speed errors.

7. An electronic device, comprising:

a processor; and the number of the first and second groups,

a memory for storing executable instructions of the processor;

wherein the processor is configured to execute the intelligent control method for cutting chatter suppression of the five-axis gantry numerically controlled machining center according to any one of claims 4 to 6 through execution of the executable instructions.

8. A computer-readable storage medium on which a computer program is stored, wherein the computer program, when executed by a processor, implements the intelligent control method for cutting chatter suppression of a five-axis gantry numerically controlled machining center according to any one of claims 4 to 6.

Technical Field

The invention relates to the technical field of numerical control of machine tools, in particular to an intelligent control method for suppressing cutting chatter of a five-axis gantry numerical control machining center.

Background

When a machine tool performs product cutting machining, cutting vibration is easily caused due to reasons such as complex workpiece appearance, uneven internal structure, inappropriate cutting amount and machine tool rotation speed selection, and the like. The cutting vibration can affect the normal motion track, so that the quality and the dimensional accuracy of the surface of a machined workpiece are reduced; in addition, the vibration affects the normal cutting conditions of the tool, thereby reducing the service life of the tool, which in turn leads to a reduction in production efficiency.

Disclosure of Invention

The invention aims to provide an adaptive notch filter technology which is used for inhibiting cutting vibration generated by each feed shaft in the cutting process of a machine tool. Aiming at the vibration suppression of the motion chain of the feed shaft of the machine tool, the speed information of each feed shaft is collected in real time, the speed information is subjected to on-line Fast Fourier Transform (FFT), when the harmonic wave of the speed information in a frequency domain exceeds a certain threshold value, the internal trap function of a servo driver is started, and the resonance frequency of the current of a feed servo motor is trapped, so that the aim of suppressing the cutting vibration is fulfilled.

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention discloses an intelligent control method for suppressing cutting chatter of a five-axis gantry numerical control machining center, which adopts a self-adaptive wave trap to suppress cutting chatter, wherein the wave trap comprises the following steps: the device comprises a rotating speed detection module, a vibration frequency detection module, a speed loop PI regulation module, a self-adaptive notch filter module and a current loop PI regulation module, wherein the rotating speed detection module is used for being connected with a permanent magnet synchronous motor, detecting the space position information of each feeding shaft in real time, and calculating to obtain a rotating speed signal omega and a rotor feedback speed omega_fdb(ii) a The vibration frequency detection module receives the feedback speed omega of the rotor_fdbWith a reference value omega of the speed of rotation_refPerforming fast Fourier transform on the rotational speed difference value to calculate the vibration frequency; the speed loop PI regulation module is used for giving a given speed reference value omega_refAnd the rotor feedback speed omega output by the rotating speed detection module_fdbPerforming PI regulation on the differenced signal to output a current reference value i_ref(ii) a The adaptive notch filter module is used for receiving a reference current i_refCarrying out self-adaptive notch processing to obtain current i after notch processing^*(ii) a A current loop PI regulating module for receiving the current i after trap processing^*Performing PI regulation to generate a reference voltage U_ref。

Furthermore, the adaptive notch filter module adopts a double-T type three-parameter notch filter, and the transfer function is as follows:

wherein f is trap central frequency of the trap, unit: hertz (Hz); the width of the trap wave trap, namely the width of two sides when the amplitude is reduced by 3dB by taking the trap wave center frequency as the center, the unit is: hertz (Hz); xi is the notch depth of the wave trap, namely the amplitude ratio of the notch center frequency before and after the notch.

Still further, the adaptive notch filter module includes a notch filter center frequency calculating unit, a notch filter width parameter calculating unit, and a notch filter depth parameter calculating unit, wherein:

the central frequency calculation unit of the wave trap is used for calculating the vibration frequency f output by the vibration frequency detection module according to the input₀The center frequency f of the adaptive notch filter is obtained₀；

The width parameter calculation unit of the wave trap sets a signal threshold value H_tIf the frequency point exceeds the threshold, the vibration is considered to be caused, and the frequency point f corresponding to the set threshold is calculated₁、f₂And calculating the center frequency f of the trap₀And taking the difference value of the two threshold frequency points and twice of the larger value of the two threshold frequency points as the width parameter of the wave trap, namely:

＝2*max(f₀-f₁,f₀-f₂)

the depth parameter calculation unit of the wave trap firstly takes the depth parameterAnd calculating the maximum amplitude H after the trap₀And setting a threshold range [ H ]_tl,H_th]Judgment of H₀If the current value is not within the threshold range, introducing a correction parameter:

the corrected depth parameter is ξ_fixLambda ξ and calculating the maximum amplitude after the notch until the amplitude H₀∈[H_tl,H_th]。

The invention further discloses an intelligent control method for suppressing cutting flutter of a five-axis gantry numerical control machining center, which is used for controlling the self-adaptive notch filter and comprises the following steps:

step 1, initializing the wave trap, and controlling a main program after the initialization is finished, wherein the main program detects whether an enabling signal of the wave trap is received, and if the enabling signal is not detected, the control program is always in a detection state until the enabling signal of the wave trap is received;

step 2, after an enabling signal of the wave trap is detected, detecting the condition of sampling points, judging whether the number of the sampling points is equal to the number of preset sampling points or not, if the number of the detected sampling points is not the number of the preset sampling points, returning to the initialization state of the wave trap for re-detection until the number of the detected sampling points is consistent with the number of the preset sampling points, and entering step 3;

step 3, performing online calculation on data acquired by sampling points through an FFT online calculation module, and respectively calculating the center frequency, the width parameter and the depth parameter of the self-adaptive notch filter;

step 4, inputting the parameters calculated in the step 3 into a wave trap to complete the updating of the parameters of the wave trap

And 5, embedding the adaptive notch filter into a servo motor control circuit to notch the current vibration frequency of the feeding servo motor.

Furthermore, the speed information of each feeding shaft is collected in real time, and when the harmonic wave of the speed information in a frequency domain exceeds a preset threshold value, an enabling signal of a wave trap is triggered so as to start an internal wave trapping function of a servo driver and trap the resonant frequency of the current of the feeding servo motor.

Furthermore, the sampling points collect speed information of each feeding shaft and sample speed errors.

The invention further discloses an electronic device comprising:

a processor; and the number of the first and second groups,

a memory for storing executable instructions of the processor;

wherein the processor is configured to perform the above-described adaptive notch filter control method via execution of the executable instructions.

The invention further discloses a computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the adaptive notch filter control method described above.

Compared with the prior art, the invention has at least the following beneficial effects:

the invention relates to a servo motor adaptive notch filter technology for suppressing cutting vibration of a machine tool, which is characterized in that the technology is based on the detection of rotating speed information of each feeding shaft of the machine tool, and respectively calculates the center frequency, the width parameter and the depth parameter of an adaptive notch filter according to the online fast Fourier transform result, and the adaptive notch filter module is embedded into a servo motor control circuit to trap the current vibration frequency of a feeding servo motor, thereby achieving the purpose of suppressing the cutting vibration. Therefore, cutting vibration of the machine tool feed shaft in the cutting process is reduced, the workpiece processing quality is improved, the service life of the cutter is prolonged, and the production efficiency is improved.

Drawings

The invention will be further understood from the following description in conjunction with the accompanying drawings. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the embodiments. In the drawings, like reference numerals designate corresponding parts throughout the different views.

FIG. 1 is a control circuit diagram of a servo motor adaptive notch filter for suppressing machine tool cutting vibration according to the present invention;

FIG. 2 is a flow chart of the control of a servo motor adaptive notch filter for suppressing machine tool cutting vibration according to the present invention;

FIG. 3 is a flow chart of the adaptive notch filter module depth parameter calculation according to the present invention.

Detailed Description