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Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to solve the problem of extracting machine tool design knowledge in the construction of computer numerical control( CNC) machine tool design knowledge graph, the classification standard and labeling strategy of knowledge in the field of CNC machine tools are formulated and a domain data set was constructed. The entity recognition method based on robustly optimized BERT pretraining approach(RoBERTa) for CNC machine tool design was proposed. Firstly, RoBERTa was fine-tuned by using the data set in the field of CNC machine tools, and then the text was encoded by RoBERTa to generate a vector representation. Secondly, the bidirectional long short-term memory (BiLSTM) network was used to extract the vector features. Finally, the conditional random field (CRF) was used to infer the optimal result. The experimental results show that the F1 value of the model on the test data set is 86. 139%, the F1 value of most key entity is greater than 85%. Compared with other models, it is improved by 2% ~18%. It can be seen that this method has obvious advantages in the recognition of CNC machine tool design entities, and can identify the key entities in the machine tool design knowledge, providing a data basis for the knowledge graph. [ABSTRACT FROM AUTHOR]

Copyright of Large Electric Machine & Hydraulic Turbine is the property of Large Electric Machine & Hydraulic Turbine Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Advanced Engineering Science / Gongcheng Kexue Yu Jishu is the property of Advanced Engineering Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Large Electric Machine & Hydraulic Turbine is the property of Large Electric Machine & Hydraulic Turbine Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As an important and complex mechanical and electrical part of CNC machine tools,the position servo system is difficult to control and affected by many factors,however,its position precison will affect the machining accuracy of CNC machine tools.In this paper,we use the Compact Format Dynamic Linearization (CFDL) and traditional PI control to improve the speed loop and position loop,and then improve the design of Model-Free Adaptive Control (MFAC) by adding control items.The Matlab/ Simulink simulation results show that the proposed scheme keeps the advantages of MFAC,and improves in position following performance as well as robustness. [ABSTRACT FROM AUTHOR]

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The ball screw feed drive system of CNC(computerized numerical control)machine tools is characterized as multi-heat sources with strong time-varying heat rate. But the past work was scarely focused on the time-varying of the heat sources. This fact results in inaccuracy of predicting temperature rise and thermal error of the screw. In this paper， the heat rates of the multi-heat sources were captured by virtue of the FEM integrated with Monte Carlo method. Consequently， relationship of the ratio of each heat source to the total heat rate of the system with the running time was obtained. Then， based on heat ratios of the heat sources， the heat rates of the heat sources were determined using torque current of the servo motor in the ball screw feed drive system. Finally， numeric prediction model of temperature rise and thermal error of the screw was put forward based on finite difference method of one-dimension heat conduction equation， and the accuracy of the prediction method was verified by experimental results. [ABSTRACT FROM AUTHOR]

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents an analytical model of thermal error prediction for the ball screw based on temperatures measured on the surfaces of the heat sources. First， the analytical solution of one dimensional heat conduct equation for the screw shaft is derived based on the variable separation method. Consequently， the two bearings are considered to be fixed heat sources， and the nut is divided into a few of moving heat sources distributed continually. The temperature distribution formula on the screw shaft excited by each heat source is given， and the temperature distribution equation is acquired based on the superposition principle of heat sources. The curve fitting parameters of relation functions of temperature difference between the heat source center and the measured surface point are obtained using FEM calculation data. Then an analytical model is proposed to predict the thermal error distribution of the ball screw shaft on line. Finally， the effectiveness is verified by the experiments. [ABSTRACT FROM AUTHOR]

Based on the FOCAS function set for the FANUC numerical control system， a real-time acquisition method of worktable position and servo motor torque current for a feed drive system is proposed. The continuous functions of the worktable position and the servo motor torque current for time are determined by virtue of inserting their discrete data with the cubic spline function， respectively. Then， an algorithm is proposed to identify the friction of the feed system. The characteristics of average value and spectrum for the friction are analyzed by using the experimental data. The results demonstrate that the local average frictions take on a catenary form because the lead screw-nut pair and the bearings at both ends are not concentric. The average friction over the experimental feed length is larger when the feed speed is low， and it decreases rapidly with the increase of the feed speed. However， when the feed speed reaches a certain value， the friction force increases slightly with the increase of the feed speed. In the operating process of the feed drive system， the periodic motion of rolling elements inside the screw groove， screw waviness， balls going in and out of the screw-nut pair and circular rails in the guides can motivate the corresponding fundamental and harmonic frequencies of the friction. [ABSTRACT FROM AUTHOR]

To solve the problem that based on machine tool temperature that is comprehensively influenced by other factors, and thus the thermal error models had poor robustness, a multivariate correlative and combined thermal error model was put forward, which overall considers machine tool temperature, speed of power source, and temperature of coolant and environment. Least squares support vector (LS-SVM) method was applied to the thermal error model, and partial least squares (PLS) method was applied to extract the principal components as the input of LS-SVM, and the PLS-LSSVM thermal error combined model was then formulated. In addition, this model set the differential temperatures, relatively with initial temperatures, as the temperature variable, which is based on the process of numerical control machining and the principle of material thermal deformation, to make the thermal error compensation more accurate. It was tested on a precision machining center, whose results showed that the PLS-LSSVM thermal error model is more stable than the LS-SVM model, and more accurate than the partial least squares regression (PLSR) model. Besides, the root mean square error (RMSE) of the predictive thermal error with the PLS-LSSVM model is 5.5μm on average less than that with the PLS-LSSVM* model, which only takes into account the temperature measurements of the machine tool. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Dalian University of Technology / Dalian Ligong Daxue Xuebao is the property of Journal of Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)