基于三次正交铰杆增力机构的绿色气动夹具设计

设计一种基于三级正交铰杆增力机构的气动夹具,分析其工作原理,给出机构的增力系数和夹具输出力的计算公式.该夹具利用正交铰杆机构的角度效应,对气缸的输入力进行三次放大,增力效果明显,技术性能较为完善,克服了气压传动夹具因压力较低导致夹紧力不大的缺点,可在一定范围内代替容易产生环境污染的液压传动夹具,绿色化特征突出.     

用固定式液压缸代替铰接式液压缸的两种方法

本文介绍了固定式有杆液压缸和固定式无杆液压缸与铰杆增力机构组合而的系统。有杆液压缸采用过渡连杆与铰杆增力机构联接,无杆液压缸通过活塞径向孔中的过渡滑块与铰杆增力机构联接。用固定式液压缸代替铰接式液压缸,系统刚性显著提高,冲击及噪声显著降低。     

对称式二次正交铰杆增力机构与双活塞无杆液压缸的组合系统

介绍了一种由对称式二次铰杆增力机构与双活塞无杆液压缸组合而成的液压-机械复合传动装置的工作原理,给出了相应的力学计算公式。该系统具有结构紧凑、磨擦损失小且输出力大等优点。     

利用滚/滑-铰杆增力机构的双工位夹具设计与分析

设计两种利用铰杆增力机构的非线性气液复合传动双工位夹具。介绍其工作原理并对这两种夹具的夹紧效率及优缺点进行分析。夹具采用单缸双出杆活塞来实现双工位夹紧,中间部分由管道油路连接,具有结构简单紧凑、环境适应性强的优点。     

新型钢管打捆机械手末端钢带夹紧机构的研究与设计

末端钢带夹紧机构是新型钢管打捆机械手的重要组成部分,通过对钢带夹紧机构的理论分析和力学研究,将夹紧机构设计为增力装置,采用单臂铰杆-双臂铰杆-杠杆串联组合方式实现三次增力,既减少了机构尺寸和空间,也为了获得较大的增力比。分析了夹紧机构控制系统的工作过程,采用自动和手动两种控制模式,设计了机构控制电路和PLC控制程序。通过模拟测验,该夹紧机构可良好的完成对钢带的夹紧与松放功能。     

基于滚动高副的双边铰杆增力双向作用液压-机械复合传动压力机

介绍了一种新型的液压-机械复合传动压力机的工作原理,给出了相应的力学计算公式,并分析了其技术特性.该压力机由基于滚动高副的双边铰杆增力机构与无杆活塞式液压缸组成,在液压缸直径及要求的输出力一定的条件下,该复合传动压力机较单纯的液压传动压力机,其系统工作压力显著降低.     

基于铰杆-杠杆串联增力机构的双向浮动夹紧气动夹具

设计了一种基于铰杆-杠杆串联增力机构的双向浮动夹紧气动夹具,分析了其工作原理和性能特点,给出了夹紧力的计算公式.该夹具结构简单紧凑,且以洁净的压缩空气为工作介质,绿色化特征突出.同时由于采用二级增力机构,解决了一般气压传动夹具因压力较低而导致夹紧力不足的缺点.     

圆筒型永磁同步直线电机驱动的新型伺服压力机

提出了一种圆筒型永磁同步直线电机驱动的新型伺服压力机,采用肘杆增力机构解决了直线电机输出力不足的问题,进而扩大了直线电机式伺服压力机的公称压力.该种方式实现了采用小功率的伺服电机以获得较大吨位输出力的目的.此外,基于分散多动力思想,将圆筒型永磁同步直线电机与肘杆增力机构组成的单套动力源进行并联式机械组合,可形成2套、3...     

气动肌腱驱动的基于杆件-铰杆的对称夹具系统设计

利用气动肌腱代替传统的刚性气缸,与杠杆-铰杆增力机构进行巧妙的对称组合,可以代替传统液压夹具,具有结构紧凑、输出力大、无污染的优点。在此基础上,设计4种气动肌腱驱动的基于杆件-铰杆的对称夹具,分别介绍其工作原理,并给出相应的力学计算公式。     

SIP-160伺服压力机多杆增力机构自锁分析与优化

如果伺服压力机多杆增力机构设计不合理,压力机滑块会在上死点附近发生杆系卡死现象,其主要原因为多杆增力自锁引起。本文对多杆增力机构进行力学分析,得出多杆增力机构自锁的原因,对现有多杆增力机构提出优化方案并仿真分析,最终确定优化方案。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。