基于PowerMILL的五轴数控机床仿真与应用

通过虚拟仿真技术,基于PowerMILL软件自带的机床仿真功能,以双转头五轴数控加工中心为例,介绍五轴机床仿真模型的建立和仿真机床参数设置,并以轴流风叶片进行数控刀路仿真、优化和试切加工,验证仿真系统的有效性,确保五轴数控机床的加工效率和可靠性。     

HPM 1850U虚拟机床的构建与多轴数控加工仿真验证

HPM 1850U机床是一种能进行高速高精度加工的五轴联动加工中心,由于其结构复杂,主轴灵活且还可进行立卧转换,所以在数控加工过程中存在无法人为判断数控程序的正确性和刀轴的干涉碰撞等问题。为解决此问题,利用三维软件搭建了1850U机床实测尺寸模型,并在数控虚拟仿真加工软件VERICUT中构建该机床的虚拟仿真环境,以某叶轮为例,验证了该虚拟仿真环境的正确性。结果表明:该机床的虚拟仿真环境可实现数控加工过程动态仿真,也可以验证刀具轨迹和数控程序的正确性,并同时检验刀轴干涉的碰撞,从而缩短产品生产周期,提高生产效率,并且为其他同类型多轴机床虚拟仿真提供技术支持,也为数字化集成制造提供了虚拟仿真机床和技术。     

基于VERICUT的多轴联动数控加工仿真

采用多轴联动数控机床加工时,NC程序编写和检测难度较大。为了验证NC程序的正确性和保证加工质量,需构建虚拟加工仿真系统。利用VERICUT先进的数控加工仿真功能,以DMC60TR为原型,构建五轴数控虚拟加工仿真平台;针对机床建模仿真中的技术难点提出相应的解决方案,实现了加工过程的仿真。结果表明:通过数控仿真验证了NC程序的正确性,提高了加工效率,为多轴联动数控机床的建模仿真提供了指导。     

基于VERICUT的双转台五轴数控微型铣床建模和仿真

数控加工仿真可以形象直观地模拟数控加工的全过程,进行数控程序的检验,分析零件的可加工性和工序的合理性,从而缩短产品的研制周期.在UG软件中建立了五轴数控微型铣床的三维模型,采用CAM模块产生了人脸加工模型的五轴联动数控加工程序.基于VERICUT软件构建了双转台五轴数控微型铣床仿真环境,进行了人脸模型的加工模拟,并且通过实际加工对该虚拟仿真进行了验证.可以在该数控微型铣床虚拟平台上进一步开展五轴数控加工技术的研究.     

工作台回转式五轴数控机床虚拟样机建模与数控仿真

以工作台回转式五轴数控机床为研究对象,通过UG的CAD模块建立该机床和被加工件的虚拟模型并输出各组件的STL模型,再导入VERICUT中,完成机床在VERICUT中的虚拟建模。对建立好的虚拟模型进行设置,调用数控程序完成工作台回转式五轴数控虚拟样机的建模和仿真。     

五轴联动数控加工中旋转角的优化和选择

根据A-C双转台五轴数控联动机床的运动学模型,结合其结构及工作空间,研究了该类五轴联动数控机床的旋转角优化选择策略及其优化算法,通过仿真分析和加工实验对该算法进行了验证,为该类机床旋转角的优化选择提供了方法.     

基于NCSIMUL的五轴机床虚拟仿真技术研究

针对五轴加工机床存在程序编制复杂,人工检查困难,加工过程中易碰撞等问题,以Mikron HEM 500 U五轴加工中心机床为例,研究了双摆台五轴加工中心结构,提出了应用NCSIMUL软件构建虚拟机床的方法,搭建了虚拟加工环境,通过叶轮零件仿真加工,完成了APT刀位源文件到NC代码的自动转换,实现了零件五轴联动加工,验证...     

五轴联动机床的轨迹控制研究

在分析了目前的数控加工自动编程系统后,提出了一种以仿真实现五轴联动机床轨迹控制的新方法.该方法首先从提取加工路径信息入手,建立了仿真所需要的驱动函数.然后在ADAMS平台上,从加工起点发起仿真运动.加工过程仿真产生的各轴运动参数信息,直接为五轴联动机床的数控编程提供了控制依据.一个圆柱凸轮加工仿真的实例证明,用仿真结果替代传统控制算法,使得五轴联动机床的数控编程变得更加容易和快捷.该方法同样适合解决其它多轴联动设备的轨迹控制.     

数控机床仿真软件二次开发的新技术

复杂自由曲面的加工,数控机床运动部件之间容易发生干涉,为了满足工程实际需要,以五轴数控加工的仿真为核心研究内容,仿真过程中结合大型UG软件强大的几何造型功能,建立五坐标机床数控仿真模型,读取数控加工的G代码,经翻译并转换为机床运动部件之间的运动,对五轴联动数控机床加工复杂零件的加工过程进行了三维仿真,动态地显示机床、工件及刀具的运动,对各个运动部件之间进行干涉检查,并进行软件二次开发,读取数控G代码指令驱动机床各轴运动,对加工过程进行动态的仿真以验证数控程序的正确性,检测加工过程中的干涉和过切,避免机床和工件的损坏,大大地提高了生产效率,降低了生产成本.     

基于UG与Vericut的五轴数控编程及加工仿真

复杂曲面的五轴数控代码繁多复杂,采用人工检查、试切和机床空运行的代码检测方法耗费人力物力,造成资源浪费。针对这个问题,文章以曲面产品为例,首先在NX8.0的CAM模块里面规划生成该曲面加工的刀轨数据,再根据特定的五轴数控机床构造后置处理器,生成该曲面的五轴数控加工代码,最后在Vericut里面建立机床仿真模型,对数控代码仿真。通过仿真结果,修改了错误的数控代码,并对代码进行了优化和残留过切检查,得出了该方法在五轴数控编程、数控代码检查方面的优越性。     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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).     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.