Xikang Lu

Tool wear state monitoring under varying operating conditions is important for machining quality and production reliability. However, changes in cutting parameters can shift monitoring-signal distributions and reduce the generalization ability of data-driven models. This paper proposes a cross-condition tool wear state monitoring method based on multi-source sensor signal fusion and supervised transfer learning. X-axis vibration, Z-axis vibration, and spindle current signals are organized as multi-channel time-series inputs. A deep model integrating a multi-scale convolutional neural network, bidirectional long short-term memory, and an attention mechanism is developed to extract discriminative wear-related features. Source-domain pretraining, target-domain warm-up fine-tuning, and source-target joint fine-tuning are organized as a progressive supervised transfer procedure to improve target-condition adaptation. Experiments are conducted on a custom multi-condition dataset using an hp0 + hp1 → hp2 transfer task. Under the unified XZI input configuration, the proposed method outperforms CNN-LSTM, DANN, and CORAL. Input ablation results show that X, XZ, and XZI achieve accuracies of 0.6000, 0.7647, and 0.8588, respectively. In repeated random-seed experiments, the method obtains an Accuracy of 0.7929 ± 0.0499, a Macro-F1 of 0.7292 ± 0.0706, and a Cohen’s Kappa of 0.6542 ± 0.0840. The results demonstrate the effectiveness of multi-source sensor fusion and supervised target-condition adaptation for cross-condition tool wear monitoring.

The vibration signal of the bearing is mostly used in the fault diagnosis research of rolling bearings, and the vibration signal has the characteristics of strong non-smoothness and is easy to be disturbed by noise. This characteristic of the vibration signal has a strong adverse effect on the fault diagnosis of bearings. To improve the accuracy of bearing fault diagnosis, a rolling bearing fault diagnosis method based on the combination of a short-time Fourier transform and a convolutional neural network is proposed. Firstly, a short-time Fourier transform is performed on the original vibration signal of the bearing to obtain the time-frequency image of the vibration signal. Then, the dual model of 2D convolutional neural network which can obtain abundant fault information is built. Secondly, the obtained time-frequency image is image compressed to fit the proposed model. Finally, the images are input into the network for fault diagnosis, and the fault classification accuracy reaches 100%. The proposed model is tested by two methods: adding Gaussian noise to the time-frequency image and testing the model using bearing data from other working conditions, and the results show that the proposed method has good noise immunity and generalization, which can provide an effective diagnostic scheme for bearing fault diagnosis.