数控车床中螺纹加工控制功能的研究

介绍了数控车床螺纹加工的基本原理,主要采用光电编码器作为主轴转速的检测装置,利用步进电机驱动开环伺服系统,通过改进的逐点比较插补方法实现.并对数控车床上实现螺纹加工控制功能进行了研究.     

数控螺纹车削的单步插补控制法

分析了运动控制芯片MCX34的控制原理及单步插补实现过程，提出了基于运动控制芯片MCX314实现螺纹切削的单步插补控制法，从而实现快速，高效的螺纹加工。该方法控制过程简单 ，同步实现锥螺纹，控制精度高（0.001mm），响应快（≤1.6MHz)，脉冲确保不丢失，解决了数控螺纹车削存在的一系列关键问题。     

基于RTLinux的数控系统螺纹加工关键技术研究

分析了实时多任务操作系统RTLinux在数控系统螺纹加工设计中的应用.针对螺纹加工过程中常见的技术问题,提出了在RTLinux体系结构上,实现高精度螺纹插补的算法,给出了计数脉冲信号中断处理和柔性加减速控制的方法.实践证明,基于RTLinux的螺纹加工数控系统,既能够保证系统的实时性,同时能满足人机交互的要求.     

逐点比较法在螺纹车削中的应用

螺纹加工是数控车床的主要功能之一，为了实现这一功能，主轴上必须安装有脉冲编码器，本文介绍了在数控年床上，如何利用脉冲编码器实现螺纹的切削以及如何利用逐点比较法进行螺纹切削的插补计算和软件实现方法，为数控系统插补软件的设计提供了参考。     

数控车削三维螺纹和退尾的参数化设计及运动仿真分析

分析了三维螺纹及退尾的形成原理,结合螺纹车削成形的实现过程,运用计算机图形学、空间运动学的理论,在Pro/E Wildfire 2.0的环境下,对三维螺纹及退尾进行了精确建模和全参数化设计.应用虚拟装配与运动仿真技术,实现了在设计阶段可视地对装配进行干涉检测以及产品设计的合理性分析.     

数控车床圆弧面螺纹车削研究与程序开发

在车削直螺纹或锥螺纹功能基础上,提出了采用小线段螺纹插补实现圆弧面上螺纹车削的思想。为了求出逼近小线段坐标,采用几何算法对圆弧的圆心进行计算,确定加工圆弧的起始角和终止角,然后通过坐标变换得到逼近小线段点相对工件原点的坐标。最后结合SINUMERIK数控系统的R参数功能,实现了圆弧面螺纹车削的数控程序开发。     

基于DDA直线插补的异型螺纹宏程序加工

针对异型螺纹加工难,用常规方法难以车削加工的问题,研究了DDA直线插补的特点,提出了在DDA直线插补的思路上运用宏程序来数控车削异型螺纹,采用合理的加工工艺路线,并编出有一定实用价值的异型螺纹数控车削宏程序,实现了该类型螺纹的数控车削加工。     

多段连续变螺距螺纹的数控加工

多段连续变螺距螺纹的数控加工重庆大学机械工程一系王秋晓，马俊主题词变螺距，螺纹，数控加工多段连续变螺距螺纹的加工一直是螺纹加工中的难点，目前，一般采用特殊复杂的机械装置实现其加工。根据工厂的需要，我们开发出了一种可安装在Ｃ６１６、Ｃ６２０、Ｃ６３０等...     

硬质合金多功能螺纹立铣刀

这种立铣刀可在CNC机床上同时进行钻削加工和螺纹铣削加工，其特点是利用刀尖的端面切削刃和CNC系统的螺旋插补功能，一边向下切削一边同时加工出孔和螺纹。它适用于各种工件材料的螺纹孔加工，螺纹孔深度可根据需要进行调节，特别适合多品种、小批量生产。如果使用高硬度材质的多功能螺纹立铣刀，还能实现硬度达HRC60的高硬材料加工。与使用硬质合金钻头、丝锥或电火花加工螺纹孔相比，     

基于触摸屏和PMAC的数控系统在螺纹磨床改造中的应用

从硬件、软件两个方面论述了基于触摸屏和PMAC的数控系统的构建过程.软硬件功能实现模块化划分,各功能模块之间通过标准的接口协调工作,共同完成数控功能.所研制的系统能同时完成程序解释、插补计算、伺服控制、系统管理等任务,能对各种不同型号的螺纹工件进行磨削.最后通过实际生产检验,控制系统单轴行程轨迹精度达到1μm以下.     

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.