基于特定加工方法的锥齿轮Pr0／ENGINEER零件库设计

本文介绍了如何使用Pro／ENGINEER来模拟锥齿轮加工的彷形刨齿法，并创建了一个包含渐开线和摆线齿形的参数化锥齿轮零件库，通过在程序中改变锥齿轮的基本参数，即可自动生成具有不同基本参数的渐开线和摆线齿形锥齿轮。     

克林贝格摆线齿锥齿轮的精确参数化设计

分析了克林贝格摆线齿锥齿轮的加工特点和齿形形成原理,结合其齿长方向是产形轮长幅外摆线的锥面展成线及齿廓球面渐开线的特点,推导出相应的曲线方程。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,对克林贝格摆线齿锥齿轮进行了精确建模和全参数化设计。实验证明,该参数化建模改善了图形的修改手段,提高了设计的精确度。     

渐开线直齿锥齿轮Pro/E造型方法研究

介绍了在Pro/E环境下,实现标准渐开线直齿锥齿轮的精确造型方法和步骤,从原理出发,利用方程建立渐开线,从而保证齿形的准确性。通过建立齿轮中各变量与模数m、齿数z等基本参数的关系,实现了不同模数、齿数齿轮的快速造型,提高了设计效率。     

齿轮标准讲座(7)

1.1 一般介绍 GB11365—89《锥齿轮和准双曲面齿轮精度》中所指的锥齿轮(分度曲面为圆锥面的齿轮)主要用于一般机械行业的相交轴(两轴线相交)的齿轮传动;准双曲面齿轮一般用于汽车行业的相错轴(两轴线不平行,也不相交)的齿轮传动。 锥齿轮按齿线形状分为直齿、斜齿和曲线齿锥齿轮,直齿锥齿轮的齿线为分度圆锥面的直母线,斜齿锥齿轮其产形轮上的齿线是不通过锥顶的直线。曲线齿锥齿轮其产形轮的齿线是某种平面曲线,该齿轮又分为零度齿锥齿轮(中点螺旋角为零度的曲线齿);弧齿锥齿轮(产形轮的齿线为圆弧齿);摆线齿锥齿轮(产形轮的齿线为摆线齿);准渐开线锥齿轮(产形轮的齿线近似于渐开线)。     

复合形齿轮的耐磨性研究

本文介绍了复合形齿轮(摆线—渐开线复合齿形)的实验研究。结果表明:复合形齿轮在磨损量、磨损率及磨损点分布方面都优于渐开线齿轮,传动效率高,复合形齿轮适用于低速重载的工作环境。     

内啮合摆线转子油泵流量脉动及其转子受力的初步探讨

最近上海机床厂等单位设计并试制出了BB系列摆线转子泵(其原理、结构见《机床与液压》一九七三年第二期“摆线转子油泵”一文介绍),现试对其流量脉动及转子受力作一初步探讨。 (一)内啮合摆线齿轮泵和外啮合渐开线齿轮泵流量脉动的比较摆线齿形内啮合齿轮泵的理论流量脉动(参见图一):对于相邻二齿啮合点之间的     

渐开线齿轮Pro/E造型方法研究

介绍了在Pro/E环境下,实现渐开线齿轮精确造型的方法和步骤,提出了从原理出发,利用方程建立渐开线,从而保证了渐开线齿轮齿形的准确性.通过建立齿轮中各变量与齿轮基本参数模数m、齿数Z的关系,实现了不同模数、齿数齿轮的快速造型,以及不同变位系数的变位齿轮的快速造型.为产品的系列化结构设计及修改提供了很大的方便.     

渐开线圆柱齿轮体积的算法研究

分析并阐述了渐开线的生成原理和特性,以及渐开线齿形的结构特点。进一步阐述了直齿、斜齿和变位3种不同类型渐开线圆柱齿形零件齿形面积与齿体积的计算方法,并推导出了相应的渐开线齿形面积与齿体积的计算公式。应用该算法的结论,可为渐开线圆柱齿形零件加工的设计计算提供极大便利。     

球面渐开线弧齿锥齿轮参数化建模

基于球面渐开线形成原理,推导出了球面渐开线的参数化方程。根据纵向齿形是弧齿锥齿轮的齿面与节锥交线的性质,建立了齿向曲线参数化方程。齿根曲线和齿顶曲线分别是齿根圆弧和齿顶圆弧,由此分别建立了齿根参数化曲线和齿顶参数化曲线方程。齿面和齿根的过渡圆角部分,通过倒角圆方法进行优化处理。针对弧齿锥齿轮轮齿端面特征,给出了精确划分轮齿有限元网格的方法。对某弧齿锥齿轮副,在MATLAB环境下获得了含齿根过渡曲面的精确轮齿有限元模型,为齿轮啮合的应力分析和修形提供了精确的数字模型。     

锥齿轮结构化网格生成方法与参数化建模仿真

针对渐开线锥齿轮建模与数值仿真的复杂性、结构化六面体网格划分困难等问题,提出渐开线锥齿轮建模与网格划分参数化方法,编程搭建锥齿轮建模与网格划分参数化仿真分析专用软件平台。运用C++语言编写参数化主程序,进行图形界面可视化设计,搭建锥齿轮主参数输入模块。通过渐开线数学模型和锥齿轮的主参数精确建立插值点位置坐标,提出锥齿轮齿廓渐开线及三维实体结构的分块化合并六面体网格生成法,实现渐开线锥齿轮精确建模、正确规整高质结构化六面体网格生成和有限元分析全过程的参数化。此平台具有渐开线直齿锥齿轮建模速度快和结构化光滑六面体网格精度高、动力学分析操作快捷方便等优点,为解决锥齿轮的有限元结构化六面体网格划分和动力学分析提供一种参数化建模与仿真平台。     

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.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。