The effects of the prior austenite grain size in deep cryogenic treatment on the hardness, the structural change and the wear resistance of D6 tool steel were investigated. The wear resistance of the cryogenically tre...The effects of the prior austenite grain size in deep cryogenic treatment on the hardness, the structural change and the wear resistance of D6 tool steel were investigated. The wear resistance of the cryogenically treated samples was determined using the pin-on-disk wear machine. The microstructural characteristics and phases present in heat treated samples were determined using SEM and XRD techniques. The results showed that the retained austenite is completely transformed to martensite during the cryogenic treatment. Besides, there is an optimum grain size of which the maximum wear resistance and hardness are obtained.展开更多
Wear is an important factor for failures of mechanical components. Current research on wear is mainly focused on experiments while the numerical simulation of wear is hardly used owing to the complexities of the wear ...Wear is an important factor for failures of mechanical components. Current research on wear is mainly focused on experiments while the numerical simulation of wear is hardly used owing to the complexities of the wear process. Explaining the effect of friction on the wear process is important, as it will lead to a deeper understanding of the evolution of wear. This study proposed a numerical method to expound the wear process in the contact between an elastic cylinder and a half-space simulating the ring-block tester. There are two difficulties during the calculation; one is that the contact shapes vary with time, causing the pressure distribution to change simultaneously and the other is the integral equation for calculating the contact pressure under different worn shapes. In the present study, the wear rate was computed using Archard's law and the wear process was calculated step by step until the specified total sliding distance was achieved. During each step of the calculation, the contact topography was updated. The simulation intuitively reproduced the contact state of change from line to surface contact throughout the wear process. Reasonable agreements on the changes of the wear scar, achieved from experiments and numerical simulations, were obtained.展开更多
Remote monitoring of tools for prediction of tool wear in cutting processes was considered, and a method of implementation of a remote-monitoring system previously developed was proposed. Sensor signals were received ...Remote monitoring of tools for prediction of tool wear in cutting processes was considered, and a method of implementation of a remote-monitoring system previously developed was proposed. Sensor signals were received and tool wear was predicted in the local system using an ART2 algorithm, while the monitoring result was transferred to the remote system via intemet. The monitoring system was installed at an on-site machine tool for monitoring three kinds of tools cutting titanium alloys, and the tool wear was evaluated on the basis of vigilances, similarities between vibration signals received and the normal patterns previously trained. A number of experiments were carried out to evaluate the performance of the proposed system, and the results show that the wears of finishing-cut tools are successfully detected when the moving average vigilance becomes lower than the critical vigilance, thus the appropriate tool replacement time is notified before the breakage.展开更多
文摘The effects of the prior austenite grain size in deep cryogenic treatment on the hardness, the structural change and the wear resistance of D6 tool steel were investigated. The wear resistance of the cryogenically treated samples was determined using the pin-on-disk wear machine. The microstructural characteristics and phases present in heat treated samples were determined using SEM and XRD techniques. The results showed that the retained austenite is completely transformed to martensite during the cryogenic treatment. Besides, there is an optimum grain size of which the maximum wear resistance and hardness are obtained.
基金financial support from the National Nature Science Foundation of China (No.51575190)
文摘Wear is an important factor for failures of mechanical components. Current research on wear is mainly focused on experiments while the numerical simulation of wear is hardly used owing to the complexities of the wear process. Explaining the effect of friction on the wear process is important, as it will lead to a deeper understanding of the evolution of wear. This study proposed a numerical method to expound the wear process in the contact between an elastic cylinder and a half-space simulating the ring-block tester. There are two difficulties during the calculation; one is that the contact shapes vary with time, causing the pressure distribution to change simultaneously and the other is the integral equation for calculating the contact pressure under different worn shapes. In the present study, the wear rate was computed using Archard's law and the wear process was calculated step by step until the specified total sliding distance was achieved. During each step of the calculation, the contact topography was updated. The simulation intuitively reproduced the contact state of change from line to surface contact throughout the wear process. Reasonable agreements on the changes of the wear scar, achieved from experiments and numerical simulations, were obtained.
基金supported by Changwon National University in 2009-2010
文摘Remote monitoring of tools for prediction of tool wear in cutting processes was considered, and a method of implementation of a remote-monitoring system previously developed was proposed. Sensor signals were received and tool wear was predicted in the local system using an ART2 algorithm, while the monitoring result was transferred to the remote system via intemet. The monitoring system was installed at an on-site machine tool for monitoring three kinds of tools cutting titanium alloys, and the tool wear was evaluated on the basis of vigilances, similarities between vibration signals received and the normal patterns previously trained. A number of experiments were carried out to evaluate the performance of the proposed system, and the results show that the wears of finishing-cut tools are successfully detected when the moving average vigilance becomes lower than the critical vigilance, thus the appropriate tool replacement time is notified before the breakage.
