基于ANSYS分析的液压动力卡盘力学性能的研究

目前,我国液压动力卡盘的研究相对落后,特别是力学性能研究的缺乏严重影响着卡盘夹紧力和传递精度的提升,这严重制约着我国数控机床的发展,因此对液压动力卡盘力学性能的研究迫在眉睫。提出基于ANSYS软件分析液压动力卡盘力学性能的方法,对楔心套、盘体、滑座及工件的接触方式进行定义,对螺栓连接进行模拟,对工作载荷下卡盘的应力和位移进行分析,为后续失效性等的分析奠定基础。另外,利用ANSYS软件对夹紧力进行分析,并与试验结果、理论计算进行比对,验证所提出的力学性能分析方法的正确性。     

液压动力卡盘综合试验机的开发

由于动力卡盘存在使用寿命短、易故障的缺点,严重影响了我国高速高精机床的生产及应用。针对存在的问题,研发液压动力卡盘综合试验机,旨在更加高效地检测液压精密动力卡盘各项性能指标,为动力卡盘综合性能的提升奠定基础。对液压动力卡盘的结构进行介绍,主要从主轴基本参数、液压系统和检测系统装置三方面对液压动力卡盘综合试验机总方案进行设计,通过对比采集得到的测试机的性能指标数据,验证了液压精密动力卡盘几何精度、卡盘精度、1μm高速夹持精度、夹紧力和极限转速等项目检测要求。这为提高高速精密动力卡盘的各项性能指标奠定了良好的基础,具有较好的应用价值。     

动力卡盘的设计与计算

文章介绍了三爪动力卡盘的工作原理及其设计计算.通过力的平衡方程,得出夹紧力与推拉力的关系.讨论了夹紧力和极限转速是卡盘设计的理论基础.     

以数控车床为本体的液压实验台设计与实现

设计一台液压实验台,以带有液压卡盘夹紧系统的数控车床为本体,利用液压站的动力驱动尾座,并统一用PLC控制液压卡盘及液压尾座的运动。为了方便学生开展液压实验,特别是机电液的联调实验,将PLC、节流阀、压力表等部件整合到单独的操作台上。此设计在保证液压卡盘夹紧系统正常工作的前提下,挖掘了设备的潜力,拓展了其功能,并且将液压实验与数控设备相结合的思路亦可供同行参考。     

液压动力卡盘的结构和性能分析

在CNC车床和自动车床上,使用液压动力卡盘来实现工件的自动夹紧.液压动力卡盘有多种结构型式,其性能也有所不同.文章分析、介绍了三种常用的液压动力卡盘的结构和性能特点.     

一种内置式弹簧顶尖与端面定位弹性卡头液压夹紧卡盘

介绍一种结构紧凑的内置式弹簧顶尖与端面定位弹性卡头液压夹紧卡盘,可以增加机床加工工件的长度,进行精确的轴向和径向定位,夹紧力稳定、可靠,并用实例说明了卡盘的应用效果。     

正倒立车设计及关键技术研究

为实现盘类零件的自动化加工,设计具有上下双主轴的正倒立车的主机结构及机械传动机构。为克服卡盘卡爪间隙导致的工件轴向跳动误差,研究斜柱后拉式卡盘的工作原理,推导其夹紧力和后拉力的计算公式。为实现正倒立车自动化下料功能,在刀架的工位上设计气钳机构,并研究具有气钳机构刀架的刀具干涉图。设计正倒立车控制主轴卡盘和刀架松开夹紧动作的液压气动系统。以汽车刹车盘零件为典型应用实例,分析基于正倒立车的盘类零件的加工工艺。     

大孔径气动卡盘的研制

依据气压传动原理,研制了一种用于具有主轴定位功能的大型CNC车床配套的大孔径气动三爪自动定心卡盘.不同于国内现有气动卡盘,新研制的大孔径气动卡盘体为环形,卡盘体内设有创新设计的夹紧力调整装置和卡爪夹紧位置传感装置,卡爪快进和慢进双程驱动.其夹紧力调整装置、卡爪夹紧位置传感装置和卡爪双程驱动均为机械结构,性能可靠,调整便捷.文中详细论述了大孔径气动卡盘主要的设计创新点、关键部位的结构设计制造要点.     

水泵试验台液压夹紧装置设计

从系统机构设计、夹紧力分析、液压系统设计和电气控制原理等方面,阐述了水泵试验台液压夹紧装置的设计构造过程.为了保证试验时不发生泄漏现象,在管道联接端面采用抠槽密封处理技术,并对液压夹紧力进行计算与分析,得出在6.4 MPa的压力下,液压夹紧力约为88.238 kN,液压缸提供的最小工作压力为17.563 MPa.现场试验结果表明:与传统法兰联接方式相比,在规定试验压力下,该夹紧装置无泄漏现象,联接端面水力损失减小约0.156%,自动化程度高,水泵出厂检测台数增加约1.5倍,大幅度改善了水泵出厂检测的效率.     

轴箱体内孔加工圆柱度超差分析及夹紧力计算

在轴箱体零件加工过程中存在内孔圆柱度超差现象。初步分析认为是四爪卡盘夹紧工件引起的夹紧变形所致。文章分别分析计算了在一定切削用量下精车轴箱体端面及内孔时需要的夹紧力、用四爪卡盘夹紧工件实际产生的夹紧力及其引起的变形，利用材料力学、弹性力学相关定律，推导出由夹紧变形引起的形状误差的计算公式，确定了轴箱体内孔加工圆柱度超差的原因，并提出了改进措施。     

Rheology Feature of Simple Metal Melt

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.     

Microstructures and Mechanical Properties of a Newly Developed Austenitic Heat Resistant Steel

The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.     

The 15th Global Foundry Sourcing Conference 2014held in Qingdao China

Organized by Suppliers China Co., Ltd and co-organized by the National Technical Committee 54 on Foundry of Standardization Administration of China, the 15th Global Foundry Sourcing Conference 2014 （hereinafter referred to as FSC 2014） was successfully held on Sep. 23rd in Grand Regency Hotel, Qingdao. More than 500 delegates from home and abroad attended this conference, including over 130 purchasers from 20 countries and 380 domestic and foreign suppliers.     

Secondary Recrystallization Behaviors of Grain-Oriented 6.5 wt% Silicon Steel Sheets Produced by Rolling and Nitriding Processes

By rolling and nitriding processes, 0.23- to 0.3-mm-thick grain-oriented 6.5 wt% silicon steel sheets were produced. The core losses of grain-oriented 6.5 wt% silicon steel at frequencies ranging from 400 Hz to 20 k Hz were lower than that of the grain-oriented 3 wt% silicon steel with the same thickness by 16.6–35.8%. The secondary recrystallization behavior was investigated by scanning electron microscopy, energy-dispersive spectroscopy, and electron backscattered diffraction. The results show that the secondary recrystallization in high-silicon steel sheets develops more completely as the nitrogen content increases after nitriding, secondary recrystallized grain sizes become larger, and the sharpness of Goss texture increases. Because more {110}116 grains in the subsurface and the central layer of the sheets have a lot of 20°–45° high-energy boundaries in addition to Goss grains, {110}116 can be the main component through selective growth during secondary recrystallization when the inhibitor quantity is not enough and inhibitor intensity is weaker. The increases in nitrogen content can increase the inhibitor intensity and hinder abnormal growth of a mount of {110}116 grains and therefore enhance the sharpness of Goss texture.     

Laser Cladded TiCN Coatings on the Surface of Titanium

Laser cladded coatings of TiCN were produced on the surface of titanium. To obtain the optimal techniques, several conditions were tested by varying the laser scanning rate. The choice of shielding gas was also studied. The cladded coatings were then evaluated from the surface mechanics point of view based on their microhardness. The microstructure of some interesting samples was investigated by optical micrographs (OM). The results showed that under the condition of fixed pulse frequency and pulse width, the laser scanning rate and the shielding gas are the main factors influencing the components of coatings. TiCN coatings were decompounded and oxidized during the cladding process in the condition of no shielding gas of N2. X-ray diffraction results indicated that the composite coatings composed of TiCN, TiC, Ti2N, and TiO2 were produced using appropriate techniques. The results indicated that the best condition in terms of the surface microhardness is obtained when the scanning rate is 1.5mm / s, the pulse frequency is 15Hz, the pulse width is 3.0ms, and N2 is chosen as the shielding gas. The microhardness of the composite coatings is about 1331kg · mm - 2, which is about 4 times that of the substrate. The optical micrographs indicated that the cladding zone is made up of TiCN, TiO2, and some interdendritic Ti, but the diffusion zone mainly consists of the dendrites phase, and the cladded depth is about 80?滋m, which is more than 2 times that of the laser nitrided sample. There were no microcracks or air bubbles in the cladded sample, which was cladded using the above optimal techniques.     

Microstructure and Mechanical Properties of X80 Pipeline Steel Joints by Friction Stir Welding Under Various Cooling Conditions

X80 pipeline steel plates were friction stir welded(FSW) under air, water, liquid CO_2 + water, and liquid CO_2 cooling conditions, producing defect-free welds. The microstructural evolution and mechanical properties of these FSW joints were studied. Coarse granular bainite was observed in the nugget zone(NZ) under air cooling, and lath bainite and lath martensite increased signifi cantly as the cooling medium temperature reduced. In particular, under the liquid CO_2 cooling condition, a dual phase structure of lath martensite and fi ne ferrite appeared in the NZ. Compared to the case under air cooling, a strong shear texture was identifi ed in the NZs under other rapid cooling conditions, because the partial deformation at elevated temperature was retained through higher cooling rates. Under liquid CO_2 cooling, the highest transverse tensile strength and elongation of the joint reached 92% and 82% of those of the basal metal(BM), respectively, due to the weak tempering softening. A maximum impact energy of up to 93% of that of the BM was obtained in the NZ under liquid CO_2 cooling, which was attributed to the operation of the dual phase of lath martensite and fi ne ferrite.     

INDUSTRY NEWS

China Securities News reported on March 21, 2014： Guangdong Hongtu Wuhan Die Casting Co., Ltd. （Wuhan Hongtu）, a wholly owned subsidiary of Guangdong Hongtu Technology （Holdings） Co., Ltd., held a groundbreaking ceremony recently. With the registered capital of 50 million Yuan, Wuhan Hongtu has a total land area of 100,000 square meters and a plant construction area of 72,000 square meters. It is expected to have a production capacity of about 30,000 tonnes of aluminum castings annually after it is put into production.     

Microstructure,Mechanical Properties and Corrosion Behavior of Extruded Mg–Zn–Ag Alloys with Single-Phase Structure

Mg–Zn–Ag alloys have been extensively studied in recent years for potential biodegradable implants due to their unique mechanical properties,biodegradability and biocompatibility.In the present study,Mg–3Zn-x Ag(wt%,x=0.2,0.5 and0.8)alloys with single-phase crystal structure were prepared by backward extrusion at 340°C.The addition of Ag element into Mg–3Zn slightly influences the ultimate tensile strength and microstructure,but the elongation firstly increases from12%to 19.8%and then decreases from 19.8%to 9.9%with the increment of Ag concentration.The tensile yield strength,ultimate tensile strength and elongation of Mg–3Zn–0.2Ag alloy reach up to 142,234 MPa and 19.8%,respectively,which are the best mechanical performance of Mg–Zn–Ag alloys in the present work.The extruded Mg–3Zn–0.2Ag alloy also possesses the best corrosion behavior with the corresponding corrosion rate of 3.2 mm/year in immersion test,which could be explained by the single-phase and uniformly distributed grain structure,and the fewer twinning.     

Growth Morphologies of a Binary Alloy with Low Anisotropy in Directional Solidification

Two new classes of growth morphologies, called doublons and seaweed, were simulated using a phase-field method. The evolution of doublon and seaweed morphologies was obtained in directional solidification. The influence of orientation and velocity on the growth morphology was investigated. It was indicated that doublons preferred growing with its crystallographic axis aligned with the heat flow direction. Seaweed, on the other hand, could be obtained by tilting the crystalline axis to 45°. Stable doublons could only exist in a range of velocity regime. Beyond this regime the patterns formed would be unstable. The simulation results agreed with the reported experimental results qualitatively.