基于Pro/E的特殊五坐标机床的后置处理器的开发

文章分析了带倾斜转台的特殊五坐标数控机床的结构形式和坐标运动关系,给出了其详细的后置处理算法,并基于Pro/E开发出了相应的后置处理器,基于VER ICUT构建了DMU70V五联动加工中心的几何模型,通过实例仿真和实际加工实验对经开发的后置处理器生成的数控程序进行了仿真加工验证和几何干涉检验,结果表明开发的后置处理器是有效可行的。     

五坐标数控加工后置处理算法的研究

介绍了五坐标数控机床的后置处理原理，以cincinnati MilacronH5—800卧式加工中心为例，给出了针对转动坐标分别由回转工作台和主轴摆动实现的五坐标后置处理算法，并在该加工中心上得到验证。     

基于UG/POST五轴联动加工中心专用后置处理器的研发

特殊结构或采用特殊数控系统的数控机床开发专用后置处理器具有重要的现实意义和工程应用价值。文章针对国外新出现的B轴倾斜45°的特殊双转台结构五轴联动加工中心系统地推导了其后置处理的相关算法,包括旋转角度的计算、坐标变换矩阵推导和新刀位点坐标的计算等;通过结合UG/Post Builder后置处理器开发工具和上述后置处理算法,开发了该机床的专用后置处理器,并通过试验进一步验证了该后置处理器的正确性和实用性。     

摆头转台五轴机床倾斜面加工的后处理研究

针对五轴机床加工带倾斜面类零件时使用刀尖跟随功能,不能输出圆弧插补且加工时没有锁定旋转轴导致加工精度差及刚性不高的问题,采用五轴联动数控系统的倾斜面加工功能,提出了基于齐次坐标变换的后处理算法。通过在加工时将工件坐标系围绕原点进行旋转使X/Y平面与加工平面平行,然后利用齐次变换矩阵,分析摆头转台混合型五轴数控机床空间运动坐标系,并对其进行齐次变换运算得到机床运动坐标。最后,使用UG NX8.5/Post Builder编写后处理文件,通过NC代码分析、程序仿真及实际加工验证了后处理方法的正确性。     

MORI SEIKI 1500S车铣复合机床后置处理算法的研究

车铣复合机床与传统的五轴联动机床在结构上有区别,所控制的轴数超过5个。因此,在开发后置处理过程当中,与传统的五轴机床有较大区别,需要根据不同的功能来分析不同的运动链。文章主要以1500S车铣复合机床为例,详细介绍该类机床后置处理开发过程。首先建立MORI SEIKI车铣数控机床的运动坐标系,根据运动链分析及坐标变换,推导出MORI SEIKI机床的转角计算公式和坐标变换公式,分析了回转角在各个象限的取值;利用JAVA语言开发出MORI SEIKI 1500S数控机床的专用后置处理软件,并通过某叶片仿真加工验证了该后置处理算法的正确性。该研究不仅为用户解决了软件使用问题,也为车铣复合类多轴机床提供了后置处理开发思路。     

摆头转台五轴数控机床RTCP算法的研究

在五轴数控机床加工中,由于旋转运动的影响,机床各轴线性插补的合成运动会使实际刀位运动偏离编程直线,造成编程直线和机床实际运动轨迹之间产生了误差,该误差被称为非线性误差。在对摆头转台五轴数控机床运动求解进行研究的基础上,基于机床的运动求解模型,分析了五坐标加工中的非线性误差的数学模型,提出了一种RTCP功能的插补算法,并通过MATLAB实例仿真验证该RTCP算法可以有效减小非线性误差,显著提高加工精度。     

RTCP功能在后置处理中的应用

文章对五坐标数控加工后置处理中的跨象限问题进行了研究,给出了旋转轴为BC轴的五坐标数控机床的后置处理公式,分析了软RTCP功能的基本原理,给出了软RTCP功能算法流程.为了验证文中提出的软RTCP功能算法的正确性,还在VERICUT软件中构建了机床模型,针对一闭式叶轮的封闭流道进行了仿真加工.仿真试验表明,文中提出的算法可以很好的解决后置处理中的跨象限问题.     

倾斜回转工作台五坐标数控机床后置处理

介绍一种旋转工作台倾斜的特殊五坐标数控机床,分析其结构和运动特点;利用矩阵变换的原理,建立该机床的运动坐标系统,推导出刀位文件的后置处理方法,给出转角和直角坐标的计算公式,并在某单位机床上得到验证。该推导思路和方法可用于其他特殊结构的五坐标机床。     

五坐标数控加工后置处理

五坐标数控加工后置处理西北工业大学刘雄伟，王增强，杨海成主题词五坐标联动，数控加工，后置处理１引言五坐标数控加工是指数控机床主轴的五个运动坐标同时作线性插补运动，使刀具走要求的空间轨迹，完成对复杂曲面零件的加工。一般来说，五坐标联动是指机床的Ｘ、Ｙ、...     

C'-B型五坐标专用机床后置处理算法的研究及实现

对C'-B型数控五坐标专用机床的后置处理算法进行了深入研究.基于ProE/CAM生成的刀具轨迹文件,利用Visual C 6.0编制了相应的后置处理算法程序.实践证明该后置处理算法程序能较好地满足该五坐标专用机床加工需求,具有重要的工程应用价值.     

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).     

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.     

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.