对附件铣头用中心出水结构的研究北大核心

附件铣头是数控加工中心的常用配置,附件头配置中心出水功能后,往往因为旋转接头的泄漏,造成使用可靠性下降,给机床使用带来隐患。设计一种附件头用中心出水部件,通过改进旋转接头的结构设计、更改旋转接头在附件头尾端的安装方式,使旋转接头不会随附件头打刀动作做往复运动,从而提升旋转接头的可靠性;通过设计多层排水结构,保证在旋转接头渗漏的情况下,泄漏的冷却液能顺利排出附件头体外。该结构可以应用在多种附件头上,使其能在任意角度实现中心出水功能。     

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。     

基于MasrerCAM的打印机通纸导板型芯的加工工艺探索

分析了打印机通纸导板塑件及其型芯结构的特点,拟定了型芯的加工刀路轨迹,利用MasterCAM 2019曲面高速加工功能,对型芯进行了粗加工、残料区加工、水平面精加工、侧面精加工及清角,高效编制了型芯的加工程序。经量产校验,打印机通纸导板型芯的加工工艺合理。     

TK42200数控镗铣床增加刀库的改造

为了解决TK42200数控镗铣床实现自动换刀的问题,将在机床上增加刀库的改造技术应用到数控机床功能扩展中。开展了换刀控制方法的分析,提出了NC和PLC相结合共同控制换刀的方法,设计了NC换刀固定循环程序和PLC控制程序。刀库改造调试后能够稳定可靠地换刀,进行换刀和产品加工的实验,实验结果表明：换刀重复精度高,产品质量合格,减轻了操作人员劳动强度,通过修改系统变量来修复刀具表使刀库操作简单了。     

应用EX—40可编程序控制器对电动刀架换刀的控制

一、前言用计算机数控装置控制普通车床,用电动刀架实现自动换刀时,需配备换刀控制装置。在原有换刀装置中采用二极管矩阵顺序控制,并利用了较多的中间继电器,由于长时间运行和频繁换刀,易发生故障;多数故障为过流现象不能换刀或电动刀架转动不停,甚至损坏刀具和工件以及分度头,造成较大的经济损失。若自动换刀功能不用,则数控装置的功能得不到充分利用,而且原来在一台车床上可加工完成的加工工序、需要分别由多台车床来完成,或需要人工换刀,生产效率低,成本高。采用EX一的可编程序控制器（PDe）,通过接口电路和数控装置连…     

加工中心自动换刀程序的设计与调试

简述了加工中心的数控系统组成和自动换刀过程,依据自动换刀过程要求,利用数控系统内置PLC设计了自动换刀程序,并通过触摸屏的画面配合完成了动作调试。实际使用证明,该自动换刀系统提高了机床的可靠性和生产效率。     

加工中心分中对刀方法的研究

以Fanuc加工中心为研究对象,在深入了解Fanuc系统的宏编程处理方法后,通过分析华中数控系统分中对刀方法的原理,提出利用宏程序设计分中程序来实现分中对刀。经实际验证,该方法达到了预期的结果,简化了算法,提高了对刀的速度,效果良好。     

金斯伯里公司动力头附件选登

电机驱动铣削主轴附件 主轴转数为1800,3600和7200转/分的精铣附件,其上有凸轮动作的气阀,通过气缸使铣刀在回程时让刀(通用附件)。     

船用螺旋桨数控加工干涉仿真及刀轴方向控制技术研究

干涉检测是螺旋桨数控加工中的关键问题,如果在加工过程中发生干涉,会破坏机床甚至造成重大损失。基于UG软件,构建了螺旋桨加工仿真平台,利用该平台进行螺旋桨加工过程仿真和干涉分析;在虚拟环境中,检验数控程序是否干涉;针对虚拟仿真过程中发现的发生干涉的刀位点,反复自动调整刀轴矢量,计算出无干涉刀轴矢量数据,优化数控程序,以避免干涉碰撞,提高了数控程序编程效率。     

基于FANUC I/O LINK轴的飞碟式刀库控制系统开发

运用FANUC I/O Link轴功能对钻攻中心的飞碟式刀库进行控制,并利用PMC窗口实时读取Z轴的机械坐标,与预先设定的参考点进行比较,判断当前Z轴是否位于可换刀位置,从而实现安全准确换刀。实践证明:利用FANUC系统的I/O Link轴控制刀库伺服电机进行选刀、换刀,大大提高换刀效率和换刀的可靠性,同时还可以提高刀库的换刀精度。     

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.     

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.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.