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- Liu, Xianli, et al.
(författare)
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Feature extraction of milling chatter based on optimized variational mode decomposition and multi-scale permutation entropy
- 2021
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Ingår i: The International Journal of Advanced Manufacturing Technology. - : Springer Nature. - 0268-3768 .- 1433-3015. ; 114:9-10, s. 2849-2862
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Tidskriftsartikel (refereegranskat)abstract
- In the milling process, chatter is easy to occur and has a very adverse impact on the quality of the workpiece and the production efficiency. A chatter feature extraction method based on optimized variational mode decomposition (OVMD) and multi-scale permutation entropy (MPE) was proposed to solve the problem that it is difficult to detect the machining chatter state during milling. The methodology presented in this article allows the occurrence of machining chatter to be effectively identified through real-time digital signal processing and analysis. First, in order to solve the problem of variational mode decomposition (VMD) parameter selection, an automatic selection method based on particle swarm optimization (PSO) and the maximum crest factor of the envelope spectrum (CE) was proposed. Then, the decomposed signal was reconstructed based on the energy ratio. In order to solve the problem that the single-scale permutation entropy (PE) cannot detect milling chatter well, the MPE was introduced to detect milling chatter. Finally, experimental verification was carried out, and the MPE of the reconstructed signals at different scales was extracted and analyzed. The results show that using the OVMD algorithm to process the signals can significantly improve the discrimination of MPE. With the increase of the scale factor, the MPE of the milling signals tends to decrease. At the same time, MPE is better than single-scale PE in chatter detection, and the MPE at scale factor of 4 is more conducive to chatter detection.
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| 2. |
- Meng, Boyang, et al.
(författare)
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Uniformity, Periodicity and Symmetry Characteristics of Forces Fluctuation in Helical-Edge Milling Cutter
- 2021
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Ingår i: Applied Sciences. - : MDPI AG. - 2076-3417. ; 11:6
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Tidskriftsartikel (refereegranskat)abstract
- Under most processing conditions, the milling force is expected to be stable and not to fluctuate, in order to improve the processing quality. This study focuses on analyzing the force fluctuation characteristics under conditions of different processing and cutter parameters. An original model is proposed to predict the force fluctuation during the milling process of a helical-edge cutter. At the same time, three force fluctuation characteristics related to the axial cutting depth and cutter parameters are determined: uniformity, periodicity and symmetry. The corresponding mathematical derivation and proof method are given for the first time through a force transformation of projecting the superposition chip thickness on a virtual cutting edge. On this basis, a fast estimation method and an accurate simulation method for force fluctuation prediction are established to quantify the intensity of force fluctuations under different parameters. Both two prediction methods and the experimental cutting tests validate the proposed theory effectively. The result shows a high potential of the proposed theory for studying the force behavior under different milling parameters or cutter parameters and at least 75% of the test workload can be reduced.
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