Y9420 Gear Chamfering Machine is ahigh efficiency machine tool designedby the Chongqing Machine ToolsWorks to meet market demand. The machineemploys the principle of cool extrusion anduses a special chamfering tool wh...Y9420 Gear Chamfering Machine is ahigh efficiency machine tool designedby the Chongqing Machine ToolsWorks to meet market demand. The machineemploys the principle of cool extrusion anduses a special chamfering tool which drivesthe work piece to rotate and achievechamfering. It features no tool tracks and noburr on the ends. Multiple cutters can beused to process cluster gears, and thechamfering can be realized on either oneside of the tooth or on both. It is an idealpiece of equipment for automobiles, machinetools and gears manufacture to chamfer anddeburr disk type gears, spur and helical shaftgears and cluster gears.展开更多
Owing to heavy dynamic and thermal loads, PCBN tools are seriously worn during hard cutting, which largely constrains the improvement of their machining performance. Therein, the chamfered structure of a cutting edge ...Owing to heavy dynamic and thermal loads, PCBN tools are seriously worn during hard cutting, which largely constrains the improvement of their machining performance. Therein, the chamfered structure of a cutting edge has a notable influence on the tool wear. Thus, a comparative study was carried out on the wear morphology and wear mechanism of PCBN tools with either a variable chamfered edge or an invariable chamfered edge. The results indicate that, for a PCBN tool with a variable chamfered edge, the rake wear area is far from the cutting edge and slowly extends toward it. A shallow large-area crater wear occurs on the rake face, and the flank wear area has a long triangular shape with a smaller wear area and width, and the cutting edge remains in a good state during the cutting process. In contrast, for a PCBN tool with an invariable chamfered edge, a deep small-area crater appears on the rake face, and the wear area is close to the cutting edge and quickly extends toward it. Thus, it is easy for chips to accumulate in the crater, resulting in large-area and high-speed wear on the flank face. In addition, the tool shows a weak wear resistance. In the initial wear stage, the rake wear mechanism of the two cutting tools is a mixture of abrasive, oxidation, and other types of wear, whereas their flank wear mechanism is dominated by abrasive wear. With an aggravation of the tool wear, the oxidation and diffusion wear mechanism are both increasingly strengthened. The rake wear of the cutter with a variable chamfered edge showed an obvious increase in the oxidation and diffusion wear, as did the flank wear of the cutter with an invariable chamfered edge. This study revealed the wear mechanism of the PCBN tool with a variable chamfered edge and provided theoretical and technological support for its popularization and application in the machining of high-hardness materials.展开更多
A discharge channel with a chamfered wall not only has application in the design of modern Hall thrusters, but also exists where the channel wall is eroded, and so is a common status for these units. In this paper, th...A discharge channel with a chamfered wall not only has application in the design of modern Hall thrusters, but also exists where the channel wall is eroded, and so is a common status for these units. In this paper, the laws and mechanisms that govern the effect of the chamfered wall on the performance of a Hall thruster are investigated. By applying both experimental measurement and particle-in-cell simulation, it is determined that there is a moderate chamfer angle that can further improve the optimal performance obtained with a straight channel. This is because the chamfering of the wall near the channel exit can enhance ion acceleration and effectively reduce ion recombination on the wall, which is favorable to the promotion of the thrust and efficiency. However, the chamfer angle should not be too large; otherwise, both the density of the propellant gas and the distribution of the plasma potential in the channel are influenced, which is undesirable for efficient propellant utilization and beam concentration. Therefore, it is suggested that the chamfer shape of the channel wall is an important factor that must be carefully considered in the design of Hall thrusters.展开更多
In order to analyze the influence of the hole chamfer on the metering performances of a Multi-hole Orifice Flowmeter and optimize the related orifice structure,a multi-hole orifice flowmeter with DN80 and throttle rat...In order to analyze the influence of the hole chamfer on the metering performances of a Multi-hole Orifice Flowmeter and optimize the related orifice structure,a multi-hole orifice flowmeter with DN80 and throttle ratio of 0.45 was considered in the present study.The flow field characteristics were determined in the framework of a CFD technique.The results show that the multi-hole orifice flowmeter with filleting transition around the throttle orifice has higher accuracy in a wide range of the space of parameters,and is more suitable for accurate measurement of fluid in process control.展开更多
文摘Y9420 Gear Chamfering Machine is ahigh efficiency machine tool designedby the Chongqing Machine ToolsWorks to meet market demand. The machineemploys the principle of cool extrusion anduses a special chamfering tool which drivesthe work piece to rotate and achievechamfering. It features no tool tracks and noburr on the ends. Multiple cutters can beused to process cluster gears, and thechamfering can be realized on either oneside of the tooth or on both. It is an idealpiece of equipment for automobiles, machinetools and gears manufacture to chamfer anddeburr disk type gears, spur and helical shaftgears and cluster gears.
基金Supported by National Natural Science Foundation of China(Grant No.51475125)Heilongjiang Provincial Natural Science Foundation of China(Grant No.E2016047)
文摘Owing to heavy dynamic and thermal loads, PCBN tools are seriously worn during hard cutting, which largely constrains the improvement of their machining performance. Therein, the chamfered structure of a cutting edge has a notable influence on the tool wear. Thus, a comparative study was carried out on the wear morphology and wear mechanism of PCBN tools with either a variable chamfered edge or an invariable chamfered edge. The results indicate that, for a PCBN tool with a variable chamfered edge, the rake wear area is far from the cutting edge and slowly extends toward it. A shallow large-area crater wear occurs on the rake face, and the flank wear area has a long triangular shape with a smaller wear area and width, and the cutting edge remains in a good state during the cutting process. In contrast, for a PCBN tool with an invariable chamfered edge, a deep small-area crater appears on the rake face, and the wear area is close to the cutting edge and quickly extends toward it. Thus, it is easy for chips to accumulate in the crater, resulting in large-area and high-speed wear on the flank face. In addition, the tool shows a weak wear resistance. In the initial wear stage, the rake wear mechanism of the two cutting tools is a mixture of abrasive, oxidation, and other types of wear, whereas their flank wear mechanism is dominated by abrasive wear. With an aggravation of the tool wear, the oxidation and diffusion wear mechanism are both increasingly strengthened. The rake wear of the cutter with a variable chamfered edge showed an obvious increase in the oxidation and diffusion wear, as did the flank wear of the cutter with an invariable chamfered edge. This study revealed the wear mechanism of the PCBN tool with a variable chamfered edge and provided theoretical and technological support for its popularization and application in the machining of high-hardness materials.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51507040,51777045 and 51736003)the Fundamental Research Funds for the Central Universities,China(Grant No.HIT.NSRIF.2015079)the Research Program,China(Grant No.JSZL2016203C006)
文摘A discharge channel with a chamfered wall not only has application in the design of modern Hall thrusters, but also exists where the channel wall is eroded, and so is a common status for these units. In this paper, the laws and mechanisms that govern the effect of the chamfered wall on the performance of a Hall thruster are investigated. By applying both experimental measurement and particle-in-cell simulation, it is determined that there is a moderate chamfer angle that can further improve the optimal performance obtained with a straight channel. This is because the chamfering of the wall near the channel exit can enhance ion acceleration and effectively reduce ion recombination on the wall, which is favorable to the promotion of the thrust and efficiency. However, the chamfer angle should not be too large; otherwise, both the density of the propellant gas and the distribution of the plasma potential in the channel are influenced, which is undesirable for efficient propellant utilization and beam concentration. Therefore, it is suggested that the chamfer shape of the channel wall is an important factor that must be carefully considered in the design of Hall thrusters.
基金supports of Hebei province high-tech industry multiplier project(No.16211702D)Chengde science and technology&development project(No.20152013).
文摘In order to analyze the influence of the hole chamfer on the metering performances of a Multi-hole Orifice Flowmeter and optimize the related orifice structure,a multi-hole orifice flowmeter with DN80 and throttle ratio of 0.45 was considered in the present study.The flow field characteristics were determined in the framework of a CFD technique.The results show that the multi-hole orifice flowmeter with filleting transition around the throttle orifice has higher accuracy in a wide range of the space of parameters,and is more suitable for accurate measurement of fluid in process control.
