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粉末高速压制技术的发展现状 被引量:19
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作者 曲选辉 尹海清 《中国材料进展》 CAS CSCD 2010年第2期45-49,共5页
粉末高速压制成形(HVC)技术在2001年由瑞典HganasAB公司提出,并在瑞典Hydro-pulsor公司生产的HVC设备上实现了速度≤10m.s-1的压制成形。高速压制成形原理是通过应力波在粉体中的传播使粉末致密,该技术具有压制生坯密度高、密度分布均... 粉末高速压制成形(HVC)技术在2001年由瑞典HganasAB公司提出,并在瑞典Hydro-pulsor公司生产的HVC设备上实现了速度≤10m.s-1的压制成形。高速压制成形原理是通过应力波在粉体中的传播使粉末致密,该技术具有压制生坯密度高、密度分布均匀、产品综合性能优异的特点,可以通过连续多次压制实现小设备压制大零件等,所以备受青睐。多个国家的研究者开展了相应的研究工作,材料涉及铁、铜、钛及其合金、磁性材料、陶瓷材料等。高速压制的粉末致密化机理不同于传统压制,今后还有待进一步深入开展研究。 展开更多
关键词 粉末高速压制 压制速度 生坯密度 多次压制 应力波
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基于响应面法的鱼类饲料颗粒密度预测模型研究 被引量:5
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作者 宋欣 李艳聪 +2 位作者 万志生 李艳琳 郑爽爽 《饲料工业》 北大核心 2015年第3期27-31,共5页
为揭示环模压缩比和压制速度对饲料颗粒密度的影响和实现颗粒密度预测,文章采用响应面试验设计方法进行饲料颗粒压制模拟试验。根据试验结果拟合出饲料颗粒密度的二阶响应面模型,利用该响应面模型进行了影响规律分析和饲料颗粒密度预测... 为揭示环模压缩比和压制速度对饲料颗粒密度的影响和实现颗粒密度预测,文章采用响应面试验设计方法进行饲料颗粒压制模拟试验。根据试验结果拟合出饲料颗粒密度的二阶响应面模型,利用该响应面模型进行了影响规律分析和饲料颗粒密度预测正确性验证。结果表明利用该模型进行颗粒密度预测具备一定的准确性,影响规律分析结论可为成型设备主要结构参数的优化和饲料成型工艺方案的选择提供了理论依据。 展开更多
关键词 颗粒密度 压缩比 压制速度 响应面模型
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PH4600和PH7200型全自动液压压砖机液压系统综合分析 被引量:9
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作者 冯长印 秦杰 许建清 《陶瓷》 CAS 2003年第1期40-45,共6页
重点分析了Sacmi公司威力 (Power)系列陶瓷砖自动液压压砖机液压原理、技术创新点。
关键词 PH4600型 PH7200型 全自动液压压砖机 液压系统 柔性压制 调节压制速度 比例控制 机械飞轮
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Influence of particle size on property of Ti-6Al-4V alloy prepared by high-velocity compaction 被引量:7
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作者 闫志巧 陈峰 +1 位作者 蔡一湘 尹健 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第2期361-365,共5页
Three Ti-6Al-4V alloy powders with median diameters of 103, 66 and 44 pm, respectively, were pressed by high-velocity compaction (HVC) technology and then sintered in vacuum. The effects of particle sizes on forming... Three Ti-6Al-4V alloy powders with median diameters of 103, 66 and 44 pm, respectively, were pressed by high-velocity compaction (HVC) technology and then sintered in vacuum. The effects of particle sizes on forming as well as properties of sintered samples were investigated. The results show that fine powders are more difficult to press than coarse powders and its compact density is lower too. But the sintered density of fine powders is obviously higher than that of coarse powders. Compared with the powders with 103 and 66 ~un in diameter, the green density with 44 ~rn diameter powders is lower, which is 85.1% of theoretical density (TD) at an impact energy of 913 J. After sintering at 1300 ~C for 2,5 h, the sintered density of the compacts with 44 pm diameter powders is the highest, and reaches 98.2% of TD. Moreover, the sintered sample with 44 pan in diameter has the highest hardness and compressive strength, which are HV 354 and 1265 MPa, respectively. 展开更多
关键词 TI6AL4V high-velocity compaction (HVC) green density SINTERING
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A NEW CONTROL METHOD FOR ULTRASONIC MOTOR 被引量:1
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作者 魏守水 赵向东 赵淳生 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1999年第2期109-113,共5页
A new method for the control of the speed of an ultrasonic motor and its implementation are proposed. The method is merely used by detecting the time when motor′s monitor signal reaches a non zero reference valu... A new method for the control of the speed of an ultrasonic motor and its implementation are proposed. The method is merely used by detecting the time when motor′s monitor signal reaches a non zero reference value than a zero one, the direction, in which the driving frequency of the motor should be shifted, can be promptly calculated. With the aid of a CPU and the phase locked frequency doubling technique, the motor can be steadily driven in a wide range of frequency and the optimum frequency can be captured rapidly and precisely. Experiment shows that the above method is available. 展开更多
关键词 ultrasonic motor computer control piezoelectric actuator phase locked loop speed control
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YB32—100C四柱液压机
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《机电新产品导报》 1994年第10期34-34,共1页
本机器适用于塑料性材料的压制工艺,如冲压、弯曲、翻边、薄板拉伸等,也可从事校正、压装、砂轮成形、冷挤金属零件成形、塑料制品及粉末制品的压制成形工艺。 本机品的工作压力、压制速度、空载下行、减速行程均可根据需要在规定的范... 本机器适用于塑料性材料的压制工艺,如冲压、弯曲、翻边、薄板拉伸等,也可从事校正、压装、砂轮成形、冷挤金属零件成形、塑料制品及粉末制品的压制成形工艺。 本机品的工作压力、压制速度、空载下行、减速行程均可根据需要在规定的范围内进行调整。 展开更多
关键词 四柱液压机 减速行程 薄板拉伸 压制工艺 压制成形 压制速度 粉末制品 工作压力 工艺方式 塑料制品
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Isothermal extrusion speed curve design for porthole die of hollow aluminium profile based on PID algorithm and finite element simulations 被引量:3
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作者 Jie YI Zhi-wen LIU Wen-qi ZENG 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2021年第7期1939-1950,共12页
The isothermal extrusion process of hollow aluminium profile was investigated using incremental proportional-integral-derivative(PID)control algorithm and finite element simulations.The range of extrusion speed was de... The isothermal extrusion process of hollow aluminium profile was investigated using incremental proportional-integral-derivative(PID)control algorithm and finite element simulations.The range of extrusion speed was determined by considering the maximum extrusion load and production efficiency.By taking the optimal solution temperature of the secondary phase as the target temperature,the extrusion speed–stroke curve for realizing the isothermal extrusion of the aluminium profile was obtained.Results show that in the traditional constant extrusion speed process,the average temperature of the cross-section of the aluminium profile at the die exit rapidly increases and then slowly rises with the increase in ram displacement.As the extrusion speed increases,the temperature difference at the die exit of the profile along the extrusion direction increases.The exit temperature difference between the front and back ends of the extrudate along the extrusion direction obtained by adopting isothermal extrusion is about 6.9℃.Furthermore,the heat generated by plastic deformation and friction during extrusion is balanced with the heat transfer from the workpiece to the container,porthole die and external environment. 展开更多
关键词 isothermal control extrusion speed curve porthole die extrusion PID control heat balance
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Control strategy for multi-pump emulsion power station in coal mine face 被引量:7
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作者 LI Wen-ying WEI Jin-hong 《Journal of Coal Science & Engineering(China)》 2011年第4期443-446,共4页
Shearer and hydraulic support are matching equipments. To increase the operating speed of the shearer, the following speed of hydraulic support must be increased. This means increasing the volume of flow from emulsion... Shearer and hydraulic support are matching equipments. To increase the operating speed of the shearer, the following speed of hydraulic support must be increased. This means increasing the volume of flow from emulsion power station. Analyzing the operating characteristics of hydraulic supports, the number of simultaneously operating supports is obtained by means of pressure parameter and time history at a certain time, which is a theory base for development of control system to multi-pump emulsion power station. 展开更多
关键词 emulsion pump mining face hydraulic support control algorithm
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NOVEL SENSORLESS VECTOR CONTROL SYSTEM OF INDUCTION MACHINE BASED ON FLUX OBSERVER IN FIELD WEAKENING 被引量:1
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作者 邹积勇 许镇琳 孙凯 《Transactions of Tianjin University》 EI CAS 2006年第1期1-5,共5页
A speed-sensorless vector control system for induction machines (IMs)is presented, According to the vector control theory of IMs, the rotor flux is estimated based on a flux observer,and the speed is estimated throu... A speed-sensorless vector control system for induction machines (IMs)is presented, According to the vector control theory of IMs, the rotor flux is estimated based on a flux observer,and the speed is estimated through the method of q-axis rotor flux converging on zero with proportional integral regulator, A 0.75 kW,50 Hz,two-pole induction machine was used in the simulation and experimental verification, The simulation model was constructed in Matlab. A series of tests were performed in the field weakening region, for both no-load and loaded operation. The estimated speed tracks the actual speed well in the based speed region and field weakening region ( 1 per unit value to 4 per unit value). The small estimation error of residual speed is due to the existence of slip. 展开更多
关键词 induction machines (IMs) sensorless vector control flux observer speed estimation
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Numerical Simulation on a Throttle Governing System with Hydraulic Butterfly Valves in a Marine Environment 被引量:2
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作者 万会雄 方俊 黄辉 《Journal of Marine Science and Application》 2010年第4期403-409,共7页
Hydraulic butterfly valves have been widely applied in marine engineering because of their large switching torque, low pressure loss and suitability for large and medium diameter pipelines. Due to control problems res... Hydraulic butterfly valves have been widely applied in marine engineering because of their large switching torque, low pressure loss and suitability for large and medium diameter pipelines. Due to control problems resulting from switching angular speeds of the hydraulic butterfly valve, a throttle-governing control mode has been widely adopted, and detailed analysis has been carried out worldwide on the structural principle concerning speed-regulation and the load torque on the shaft while opening or closing a hydraulic butterfly valve. However relevant reports have yet been published on the change law, the error and the influencing factors of the rotational angular velocity of the hydraulic butterfly valve while opening and closing. In this article, research was based on some common specifications of a hydraulic butterfly valve with a symmetrical valve flap existing in a marine environment. The throttle governing system supplied by the accumulator to achieve the switching of the hydraulic control valve was adopted, and the mathematical models of the system were established in the actual conditions while the numerical simulations took place. The simulation results and analysis show that the rotational angular velocity and the error of the hydraulic butterfly valve while switching is influenced greatly by the drainage amount of the accumulator, resulting in pressure loss in the pipeline, the temperature of hydraulic medium and the load of the hydraulic butterfly valve. The simulation results and analysis provide a theoretical basis for the choice of the total capacity of the accumulator and pipeline diameters in a throttle governing system with a hydraulic butterfly valve.It also determines the type and specification of the hydraulic butterfly valve and the design of motion parameters of the transported fluid. 展开更多
关键词 hydraulic butterfly valve throttle governing switching angular speed load characteristics numerical simulation
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Multi-spacecraft observations of earthward flow bursts 被引量:8
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作者 MA YuDuan CAO JinBin +3 位作者 REME Henry DANDOURAS Iannis DUNLOP Malcolm LUCEK Elisabeth 《Science China(Technological Sciences)》 SCIE EI CAS 2012年第5期1305-1311,共7页
On the basis of the plasma, electric and magnetic fields jointly observed by Cluster and the Double Star TC-I spacecraft in the Earth's magnetotail, we have investigated the earthward flow bursts by introducing the m... On the basis of the plasma, electric and magnetic fields jointly observed by Cluster and the Double Star TC-I spacecraft in the Earth's magnetotail, we have investigated the earthward flow bursts by introducing the momentum equation in the X-direction in the ideal conditions of magneto hydrodynamics (MHD). One earthward flow burst with a peak in excess of 500 km/s was selected, when the four spacecraft of Cluster were located around -16 RE and TC-1 was located around -10 RE in the X-direction. The inter-spacecraft distances in Y and Z directions were smaller than the statistical spatial scales of the bursty bulk flows. When the Y components of E and -VxB were compared, there was no clear breakdown of the frozen-in condition during the earthward flow burst. With the measured plasma and magnetic parameters from two spacecraft at different positions in the magnetotail, the X component of the pressure gradient was calculated. Magnetic tension was calculated using the mag- netic field measured at four points, which could be compared with the assumed constant in the past research with single satel- lite. When the pressure gradient and the magnetic tension were put into the MHD momentum equation, some samples of the earthward flow bursts were accelerated and some were decelerated. The braking process of the earthward flow burst was more complicated than what the past results had shown. The accelerated samples accounted for about one third of the whole earth- ward flow bursts and discontinuously located among the decelerated elements. The original single earthward flow burst event might be split into several short flow bursts when it was moving to the Earth. Our results may partly illustrate that the duration of fast flows during three phases of substorm becomes short near the Earth. The results are consistent with the past results that fast flows intrude to places earthward the typical braking region. 展开更多
关键词 flow burst pressure gradient magnetic tension BRAKING
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Experimental Investigation of Effects of Distributed Riblets on Aerodynamic Performance of a Low-speed Compressor 被引量:6
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作者 MA Hongwei WEI Wei 《Journal of Thermal Science》 SCIE EI CAS CSCD 2013年第6期592-599,共8页
It is well known that riblet applied on compressor blades is a promising flow control technique. However, detailed investigation of its effects on the flow field of turbomachinery is rare in existing literatures. This... It is well known that riblet applied on compressor blades is a promising flow control technique. However, detailed investigation of its effects on the flow field of turbomachinery is rare in existing literatures. This paper presents a detailed experimental investigation of effects of distributed riblet on the flow field of an axial compressor iso- lated-rotor stage. The research was performed in a large-scale facility respectively with two configurations, in- eluding grooved hub, and grooved surface on both hub and partial suction surface. The riblet film is rectangle grooved type with a height of 0.1 ram. The flow field at 10% chord downstream from the cascade trailing edge was measured using a mini five-hole pressure probe and a total pressure probe. The testing was conducted at sev- eral operational points under two reduced rotational speeds. Stagnation pressure loss in rotational frame was cal- culated and compared with the control test in which a smooth film was applied to the corresponding position. Results show that with the grooved hub configuration at the design operation point of the lower rotational speed, the riblet film provides an obvious improvement of a 48% reduction of total pressure loss in rotational frame. Also, a distinct weaken hub comer vortex was identified. In the meantime, there exists a deviation of flow angle about 5 degrees at 20%-80% span which previously was not considered to be the affected region. 展开更多
关键词 distributed riblet large-scale compressor hub corner vortex loss reduction.
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Numerical investigation of the casing treatment mechanism with a single circumferential groove 被引量:1
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作者 SHI Ke CHEN HaiXin FU Song 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2013年第2期353-365,共13页
The paper investigates the effect of a single circumferential groove casing treatment(CGCT) on a transonic compressor rotor numerically.In particular,the effect of the groove at different axial locations on the flow f... The paper investigates the effect of a single circumferential groove casing treatment(CGCT) on a transonic compressor rotor numerically.In particular,the effect of the groove at different axial locations on the flow field is studied in detail and stall margin improvement is also discussed.The present results show that the groove close to the leading edge plays a crucial role in stabilizing the near stall flow structures and,hence,improves the stall margin.The groove at the mid-chord-section of the blade can help exchange and transfer momentums between different directions,and suppress the flow unsteadiness,leading to increased efficiency in rotor performance and extended operation range.The groove located near the blade trailing edge has limited effects on stall margin improvement and may cause additional penalty in efficiency.Through comparison with the recent work on CGCT,some common flow physics can be observed. 展开更多
关键词 compressor casing treatment circumferential groove transonic rotor stall margin
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