数控系统跟随轴在数控立式车床双层刀架改造上的应用

为了解决数控机床改造中充分利用系统功能和节省改造成本的问题,通过分析立式数控车床系统硬件配置,提出用数控系统跟随轴控制来改造双层刀架。采用NC和PLC相结合的方法控制换刀,设计了换刀子程序和换刀PLC程序。对刀架进行调试,运行结果表明:改造后该机床换刀可靠、精度高、故障率低,达到了伺服刀架的控制要求,并且充分地利用了数控系统资源,减少硬件配置,节省了改造成本。     

链式刀库的控制系统设计

针对自主研发的链式刀库及自动换刀装置(ATC),分析了其具体的换刀过程,设计了一种基于PLC和组态王的自动换刀系统.利用PLC实现了对力库运动、刀套翻转以及机械手换刀的控制;利用组态王制作了人机界面,实现了对换刀过程的监控,以及对控制系统的上位机操作.经实验证明,该控制系统性能稳定、控制精确、操作简单、监控方便,具有良好的实用价值.     

卧式加工中心接触式在机断刀检测功能开发与实现

通过PROFIBUS总线对断刀检测装置控制器进行组态;在西门子840D sl系统标准刀库界面上进行二次开发,用于设定刀表中的刀具是否需要进行断刀检测;通过NC换刀子程序和PLC程序的设定,实现NC与PLC的数据交换传输,从而将刀具是否需要检测和刀具长度等信息传送给PLC,PLC控制检测装置执行动作,并且把检测的刀具长度与实际数据进行比较,判断出是否断刀。此断刀检测装置已经应用于实际生产,可以避免由于断刀所引起的加工工件报废,从而提高效率、降低成本。     

斗笠式刀库的换刀过程控制原理与设计

通过西门子802D系统的NC程序可方便地控制刀库动作、轴移动、主轴松夹等动作，从而实现斗笠式刀库的换刀过程的完整控制。     

三菱M64数控系统在钻削中心改造中的应用

本文介绍了三菱M64数控系统的性能及其在钻削中心改造中硬件配置和PLC程序的编程.立式刀库的换刀程序;重要参数的设置及故障排除.     

链式刀库换刀控制程序设计及可靠性保障措施

链式刀库及机械手换刀系统的控制程序设计是其电气控制可靠性的重要因素之一.以高可靠性数控系统FANUC-0iD内置PMC为逻辑控制器,对链式刀库的工作原理和换刀过程作了详尽介绍后,从刀库选刀和刀具交换两方面分析了链式刀库换刀程序设计方法,进一步在细节方面提出了相关可靠性保障措施,实现了换刀程序较好的执行效果.对类似刀库机械手换刀的软件设计有一定的借鉴意义.     

自动换刀系统在大连ZTXX 30A数控铣床升级改造中的应用

某学院购买的ZTXX-30A型立式数控铣床需要手动更换刀具,而且操作人员要一直盯着,大大的降低了加工效率。为了减少加工时间,提高加工效率,结合自身维修机床的经验将ZTXX-30A型立式数控铣床改造成带有刀库的自动换刀系统,主要涉及到刀库电气控制部分设计及换刀宏程序和PMC控制程序的编制。     

基于ServoWorks CNC的全软型PLC系统研究

ServoWorks CNC中采用了软PLC控制机床的运动。通过对ServoWorks CNC中软PLC系统功能的分析,结合编制的宏程序,开发出了旋转刀库的自动换刀系统,并在实验平台上进行了程序的调试运行试验,实现了预期的目标。     

加工中心自动换刀过程PLC编程技巧

结合加工中心常见的刀库换刀过程中经常出现的换刀过程程序故障,故障点不易查找,本文采用西门子的可编程控制器来作控制元件,用西门子的S7—200PLC软件,编制出一套控制程序,使机床的刀库换刀更加可靠,灵活,故障点查找更方便快捷。     

一种固定刀库加工中心的换刀控制

介绍一种固定刀库加工中心的换刀控制原理及换刀程序。     

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.