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Tungsten carbide end mills have been widely used for titanium alloys machining, but they have severe problems of high damage rate, which lead to abnormal increase of the machining cost. Although there are many relevant research such as the material preparation and the structural design of cutting tools, the parameter optimization of titanium alloys machining process and so on, but this problems still have not been solved very well. Therefore, other possible influencing factors must also be considered. The present study focuses on the preparation of tungsten carbide end mills, an experimental study was conducted which includes the microstructure comparative analysis of the material surface layer in the different positions of tungsten carbide end mills, and the grinding effect comparison of tungsten carbide materials between different grinding parameters. The main findings include: (1) The internal micro cracks already exist in surface layer of cutting edge even these tungsten carbide end mills have not been involved in machining process; (2) In the surface layer of tungsten carbide tools, different types and levels of residual stress will be generated by different grinding process parameters, once they are engaged in the intermittent cutting process, the internal micro cracks and residual stress in the surface layer will have complex interaction with the cutting force and temperature, which can prompt the propagation of the cracks and eventually lead to catastrophic destruction of the cutting edges. It can provide an important basis for the preventive measures to eliminate the potential factors that affect the service life of the cutting tool in the fabrication stages. [ABSTRACT FROM AUTHOR]

• The degradation process of hydraulic reciprocating seal is studied. • The deteriorating parameters are extracted based on monitoring data. • Reliability prediction model of the hydraulic reciprocating seal is established. • The applicable conditions of the reliability prediction model are discussed. It is of great significance to analyze the degradation process of the hydraulic reciprocating seal and accurately predict its reliability for taking corresponding measures timely and avoiding losses and accidents. However, the degradation process of a hydraulic reciprocating seal largely depends on actual working parameters of hydraulic cylinder. Therefore, the performance degradation process of the hydraulic reciprocating seal must be studied according to the actual working process parameters of the hydraulic cylinder. In this paper, the degradation process of hydraulic reciprocating seal is studied in a specially designed experimental system. The experimental data are monitored by fiber Bragg grating (FBG) sensor, pressure sensor and friction sensor. The extraction method of performance degradation parameters of the hydraulic reciprocating seal is studied. The reliability prediction model is established, namely R-N curve, which can describe the performance deteriorating process of the hydraulic reciprocating seal. [ABSTRACT FROM AUTHOR]

In this paper, a pressure compensated sealing method is proposed to solve the problem that the piston rod seal does not have the sealing compensation capability after wear. The pressure compensation simulation and experimental research on piston rod seals with different degrees of wear were carried out. In the experimental study, the monitoring data was collected by fiber Bragg grating sensors, tension sensors, pressure sensors and displacement sensors, and the parameters that reflect the sealing performance and friction characteristics are extracted therefrom. The relationship between the compensation pressure and the parameters under different degrees of wear was analyzed. The results show that the pressure compensation sealing method can improve the sealing performance of the sealing ring. • A pressure compensation method is proposed to improve the sealing ability after the seal is worn. • The method was verified by piston rod seals with different degrees of wear. • Nine parameters were extracted from the data collected by the four sensors. • The pressure compensation seal has certain sealing compensation ability. • The relationship of the sealing performance and friction characteristics is revealed. [ABSTRACT FROM AUTHOR]