Method for acquiring modal scale factor of machine tool structure based on cutting excitation

Abstract

The invention discloses a method for acquiring a modal scale factor of a machine tool structure based on cutting excitation. The method comprises the following steps of: selecting a pulse cutting mode which comprises milling, turning and boring of a lug boss, establishing a cutting force model corresponding to the pulse cutting method, generating cutting parameters according to the cutting force model, randomly generating lug boss parameters, and calculating an auto-power spectrum of cutting force according to the cutting parameters and the lug boss parameters; judging whether the bandwidth of the auto-power spectrum covers an expected band range, judging whether the energy of the auto-power spectrum is greater than threshold energy, and if the energy is greater than the threshold energy, generating a numerical control instruction code according to the selected cutting parameters to control a machine tool to machine a testpiece to be cut; and measuring a response signal of the machine tool, calculating a cross-power spectrum array of the response signal, and calculating system poles and a modal displacement vector according to the cross-power spectrum array of the response signal by using a least-squares complex frequency-domain estimation method. By the method, the energy of exciting force can be estimated, and the modal scale factor is acquired from the cross-power spectrum array.

Description

technical field [0001] The invention relates to the technical field of structural modal parameter analysis of numerical control equipment, in particular to a method for obtaining a structural modal scale factor of a machine tool based on cutting excitation. Background technique [0002] Traditional experimental modal analysis techniques can obtain complete modal parameters, including natural frequencies, damping ratios, mode shape vectors, and mode scale factors. However, for large structures (such as bridges, high-rise buildings and heavy machine tools), the excitation method of traditional experimental modal analysis technology is difficult to implement, and the working modal analysis method using other easy-to-implement random excitation (such as environmental excitation) as the excitation method has been paid attention to. . In the working modal analysis method, assuming that the input excitation is a white noise random excitation with constant amplitude, the cross powe...

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Problems solved by technology

[0003] In the existing working modal analysis method, the modal parameters such as the natural frequency, damping ratio and mode shape vector of the structure can be identified, but the modal scale factor cannot be obtained

Since the existing working modal excitation is not artificial, it is impossible to control the position of the self-power spectrum of the excitation force, it is difficult to measure and estimate the energy of the actual excitation force, it is impossible to directly obtain the modal scaling factor from the cross-power spectrum matrix, and it is impossible to obtain the structure complete frequency response function

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