The current study investigates the behavior of wire electric discharge machining （WEDM） of the super alloy Udimet-L605 by employing sophisticated machine learning approaches. The experimental work was designed on th...The current study investigates the behavior of wire electric discharge machining （WEDM） of the super alloy Udimet-L605 by employing sophisticated machine learning approaches. The experimental work was designed on the basis of the Taguchi orthogonal L27 array, consid- ering six explanatory variables and evaluating their influ- ences on the cutting speed, wire wear ratio （WWR）, and dimensional deviation （DD）. A support vector machine （SVM） algorithm using a normalized poly-kernel and a radial-basis flow kernel is recommended for modeling the wire electric discharge machining process. The grey rela- tional analysis （GRA） approach was utilized to obtain the optimal combination of process variables simultaneously, providing the desirable outcome for the cutting speed, WWR, and DD. Scanning electron microscope and energy dispersive X-ray analyses of the samples were performed for the confirmation of the results. An SVM based on the radial-basis kernel model dominated the normalized poly- kernel model. The optimal combination of process vari- ables for a mutually desirable outcome for the cutting speed, WWR, and DD was determined as Ton1, Toffa, Ip1, WT3, SV1, and WF3. The pulse-on time is the significant variable influencing the cutting speed, WWR, and DD. The largest percentage of copper （8.66%） was observed at the highest cutting speed setting 7.05% of copper at the low of the machine compared to cutting speed setting of the machine.展开更多
To investigate the fretting wear of steel wires in hoisting ropes, specimenswere made of 6X19 point contact ropes. A model for the fretting ear was developed and a frettingwear test rig was deigned in laboratory. A se...To investigate the fretting wear of steel wires in hoisting ropes, specimenswere made of 6X19 point contact ropes. A model for the fretting ear was developed and a frettingwear test rig was deigned in laboratory. A series of experiments were performed on this test rig.The wear volume was taken as a characteristic parameter to describe the fretting wear in relation tothe contact load, reciprocating cycles and amplitude. Moreover, the wear mechanisms were discussedin the fretting process.展开更多
Caterpillar construction machines play an important part in many fields such as hydraulic and electric engineering, the construction of highway, for its particular of structure. The walking system of caterpillar const...Caterpillar construction machines play an important part in many fields such as hydraulic and electric engineering, the construction of highway, for its particular of structure. The walking system of caterpillar construction machines is always under the condition of three-body abrasive wear. The abrasive wear of walking system is very severe, which always results in damages of components or structures of walking system of caterpillar construction machines. It is very important to repair the walking system by cladding technique. The abrasive wear properties of four kinds coatings produced by the shielded flux-cored wire surfacing for the repair of the damaged components of walking system of caterpillar construction machines have been studied experimentally on an MLS-23 type wet sand rubber wheel abrasive tester. The surfaces morphologies of the abrasively worn specimens and their microstructures are investigated by transmitting electron microscopy (TEM) after wear testing. Results show that the wear mechanism of cladding metals of the flux-cored wire No.1 and the No.2 is micro-cutting while that of the No.3 and the No.4 is micro-ploughing. The four kinds of flux-cored wire coatings present great potential applications for the repairing of caterpillar construction machines in the Three Gorges Engineering.展开更多
The suitable test equipment for wire-drawing was designed. Wire-drawing tests were carried on with this equipment for TiC/Al2O3 ceramic wire-drawing die. Effect of lubrication medium and drawing velocity on the drawin...The suitable test equipment for wire-drawing was designed. Wire-drawing tests were carried on with this equipment for TiC/Al2O3 ceramic wire-drawing die. Effect of lubrication medium and drawing velocity on the drawing force was investigated. The wear mechanisms of the ceramic drawing dies were investigated. Worn bore surfaces of the ceramic drawing dies were examined by scanning electron microscopy. The results show that lubricant media have great influence on the drawing force. The drawing force is the smallest when a grease lubricant is used. But alteration of drawing velocity has scarcely any influence on the drawing force. Detailed observations and analyses of the die wear surface reveal that the most common failure of the ceramic drawing die is the wear in the invariable zone and bearing zone owing to the greater press stresses. Abrasive and adhesive wear are found to be the predominant wear mechanisms for ceramic drawing die.展开更多
The ultrasonic wedge bonding with d25 μm copper wire was achieved on Au/Ni plated Cu substrate at ambient temperature.Ultrasonic wedge bonding mechanism was investigated by using SEM/EDX,pull test,shear test and micr...The ultrasonic wedge bonding with d25 μm copper wire was achieved on Au/Ni plated Cu substrate at ambient temperature.Ultrasonic wedge bonding mechanism was investigated by using SEM/EDX,pull test,shear test and microhardness test.The results show that the thinning of the Au layer occurs directly below the center of the bonding tool with the bonding power increasing.The interdiffusion between copper wire and Au metallization during the wedge bonding is assumed negligible,and the wedge bonding is achieved by wear action induced by ultrasonic vibration.The ultrasonic power contributes to enhance the deformation of copper wire due to ultrasonic softening effect which is then followed by the strain hardening of the copper wedge bonding.展开更多
本文中研究了QBe2.0电刷丝/滑环摩擦副在不同电流强度条件下的载流摩擦学性能.研究结果显示:随着电流强度的增加,摩擦副平均摩擦系数增加,接触电阻下降,电刷丝磨损表面温度升高,平均硬度降低,电刷丝磨损表面材料软化,磨损面积增大.在摩...本文中研究了QBe2.0电刷丝/滑环摩擦副在不同电流强度条件下的载流摩擦学性能.研究结果显示:随着电流强度的增加,摩擦副平均摩擦系数增加,接触电阻下降,电刷丝磨损表面温度升高,平均硬度降低,电刷丝磨损表面材料软化,磨损面积增大.在摩擦热、电阻热和电弧热的共同作用下,刷丝磨损表面氧化磨损加剧,磨损量增加,粗糙度变大. SEM (扫描电镜)分析显示,磨屑表面出现电弧烧蚀引起的孔洞和熔融喷溅现象,电刷丝磨损面上观察到熔融产生的氧化物颗粒和龟裂现象.随着电流强度的增加,虽然摩擦副摩擦磨损性能下降,但是其接触稳定性和导电性能得到改善.展开更多
文摘The current study investigates the behavior of wire electric discharge machining （WEDM） of the super alloy Udimet-L605 by employing sophisticated machine learning approaches. The experimental work was designed on the basis of the Taguchi orthogonal L27 array, consid- ering six explanatory variables and evaluating their influ- ences on the cutting speed, wire wear ratio （WWR）, and dimensional deviation （DD）. A support vector machine （SVM） algorithm using a normalized poly-kernel and a radial-basis flow kernel is recommended for modeling the wire electric discharge machining process. The grey rela- tional analysis （GRA） approach was utilized to obtain the optimal combination of process variables simultaneously, providing the desirable outcome for the cutting speed, WWR, and DD. Scanning electron microscope and energy dispersive X-ray analyses of the samples were performed for the confirmation of the results. An SVM based on the radial-basis kernel model dominated the normalized poly- kernel model. The optimal combination of process vari- ables for a mutually desirable outcome for the cutting speed, WWR, and DD was determined as Ton1, Toffa, Ip1, WT3, SV1, and WF3. The pulse-on time is the significant variable influencing the cutting speed, WWR, and DD. The largest percentage of copper （8.66%） was observed at the highest cutting speed setting 7.05% of copper at the low of the machine compared to cutting speed setting of the machine.
基金This work was financially supported by the Ministry of Coal Industry, China(the Research Foundation of Mining Science) and the L
文摘To investigate the fretting wear of steel wires in hoisting ropes, specimenswere made of 6X19 point contact ropes. A model for the fretting ear was developed and a frettingwear test rig was deigned in laboratory. A series of experiments were performed on this test rig.The wear volume was taken as a characteristic parameter to describe the fretting wear in relation tothe contact load, reciprocating cycles and amplitude. Moreover, the wear mechanisms were discussedin the fretting process.
文摘Caterpillar construction machines play an important part in many fields such as hydraulic and electric engineering, the construction of highway, for its particular of structure. The walking system of caterpillar construction machines is always under the condition of three-body abrasive wear. The abrasive wear of walking system is very severe, which always results in damages of components or structures of walking system of caterpillar construction machines. It is very important to repair the walking system by cladding technique. The abrasive wear properties of four kinds coatings produced by the shielded flux-cored wire surfacing for the repair of the damaged components of walking system of caterpillar construction machines have been studied experimentally on an MLS-23 type wet sand rubber wheel abrasive tester. The surfaces morphologies of the abrasively worn specimens and their microstructures are investigated by transmitting electron microscopy (TEM) after wear testing. Results show that the wear mechanism of cladding metals of the flux-cored wire No.1 and the No.2 is micro-cutting while that of the No.3 and the No.4 is micro-ploughing. The four kinds of flux-cored wire coatings present great potential applications for the repairing of caterpillar construction machines in the Three Gorges Engineering.
基金Project(B0614) supported by the Natural Science Foundation of University of Jinan, ChinaProject(20030422105) supported by the Specialized Research Fund for Doctoral Program of Higher Education, China+1 种基金Project(Y2004F08) supported by the Natural Science Foundation of Shandong Province, ChinaProject(NCET-04-0622) supported by the Program for New Century Excellent Talents in University, China.
文摘The suitable test equipment for wire-drawing was designed. Wire-drawing tests were carried on with this equipment for TiC/Al2O3 ceramic wire-drawing die. Effect of lubrication medium and drawing velocity on the drawing force was investigated. The wear mechanisms of the ceramic drawing dies were investigated. Worn bore surfaces of the ceramic drawing dies were examined by scanning electron microscopy. The results show that lubricant media have great influence on the drawing force. The drawing force is the smallest when a grease lubricant is used. But alteration of drawing velocity has scarcely any influence on the drawing force. Detailed observations and analyses of the die wear surface reveal that the most common failure of the ceramic drawing die is the wear in the invariable zone and bearing zone owing to the greater press stresses. Abrasive and adhesive wear are found to be the predominant wear mechanisms for ceramic drawing die.
基金Prpject(E052104/50705021)supported by the National Natural Science Foundation of ChinaProject(2006:01504489)supported by the Development Program for Outstanding Young Teachers in HIT
文摘The ultrasonic wedge bonding with d25 μm copper wire was achieved on Au/Ni plated Cu substrate at ambient temperature.Ultrasonic wedge bonding mechanism was investigated by using SEM/EDX,pull test,shear test and microhardness test.The results show that the thinning of the Au layer occurs directly below the center of the bonding tool with the bonding power increasing.The interdiffusion between copper wire and Au metallization during the wedge bonding is assumed negligible,and the wedge bonding is achieved by wear action induced by ultrasonic vibration.The ultrasonic power contributes to enhance the deformation of copper wire due to ultrasonic softening effect which is then followed by the strain hardening of the copper wedge bonding.
文摘本文中研究了QBe2.0电刷丝/滑环摩擦副在不同电流强度条件下的载流摩擦学性能.研究结果显示:随着电流强度的增加,摩擦副平均摩擦系数增加,接触电阻下降,电刷丝磨损表面温度升高,平均硬度降低,电刷丝磨损表面材料软化,磨损面积增大.在摩擦热、电阻热和电弧热的共同作用下,刷丝磨损表面氧化磨损加剧,磨损量增加,粗糙度变大. SEM (扫描电镜)分析显示,磨屑表面出现电弧烧蚀引起的孔洞和熔融喷溅现象,电刷丝磨损面上观察到熔融产生的氧化物颗粒和龟裂现象.随着电流强度的增加,虽然摩擦副摩擦磨损性能下降,但是其接触稳定性和导电性能得到改善.
