渐开线零齿差内啮合齿轮机构的可靠性设计

文章指出了用传统的齿轮强度校核公式来校核渐开线零齿差齿轮副的不合理性,建立了新的、适用于零齿差机构的校核方程式.在此基础上,应用摄动方法和可靠性设计理论,探讨了零齿差内啮合齿轮的可靠性设计方法.文中方法可以定量地给出齿轮的可靠度并根据可靠度对齿轮进行可靠性设计,是对齿轮可靠性问题研究的一次重要探索.     

渐开线零齿差机构啮合原理与强度条件

零齿差机构的突出问题是齿轮的干涉与强度。在导出避免干涉的条件后，建立新的强度公式，给出各项检验指标，并提出切齿过程中保证精度的具体措施。     

泵用齿轮副根切重合度的公式创建

为满足外啮合齿轮泵根切齿轮副的设计需要,基于滚齿加工原理,由创建根切半径的计算公式起,推导出一套完整的根切重合度计算公式,据此分析了基本参数对该根切重合度的影响,所得结果由根切齿轮副的三维虚拟模型加以验证。结果表明,根切会使主动齿轮的齿顶点可能进入不了啮合,目前常用齿顶重合度代替根切重合度的计算方法不可靠;除模数外的其它齿形基本参数对根切重合度均有影响,其中变位系数的影响最大;采用齿条刀具的最佳齿顶圆角半径,可以保证根切重合度等于齿顶重合度;当实际的根切重合度过大时,通过降低齿条刀具齿顶圆角半径,可以改善齿轮副的传动质量等。所得根切重合度公式也能为其他常规的根切齿轮副设计,提供一种新的方法。     

渐开线及其根切齿轮的计算与编程

阐述了在数控线切割机上加工标准齿轮,变位齿轮及根切齿轮的原理和方法,介绍了齿廓曲线上各点直角坐标的计算方法,并实现了各种渐开线齿轮在线切割机上加工软件的编程。     

内啮合少齿差变厚齿轮灵敏度分析

以内啮合少齿差变厚齿轮为研究对象,利用Pro/E3.0建立内啮合少齿差变厚齿轮的简化模型,运用ANSYS软件的灵敏度分析技术对内啮合少齿差变厚齿轮的主要设计参数进行分析,得到内啮合少齿差变厚齿轮系统的固有频率、模态振型等动态特性参数以及内啮合少齿差变厚齿轮固有频率与主要结构参数之间的关系。结果表明:在满足设计要求的情况下,选择大的模数、齿数、变位系数、压力角和齿顶高系数能够有效减小内啮合少齿差变厚齿轮的固有频率,从而减少振动。为内啮合少齿差变厚齿轮传动的减振设计和噪声控制的研究提供了依据。     

渐开线及其根切齿轮的计算与编程

阐述了在数控线切割机上加工标准齿轮、变位齿轮及根切齿轮的原理和方法 ,介绍了齿廓曲线上各点直角坐标的计算方法 ,并实现了各种渐开线齿轮在线切割机上加工软件的编程     

伺服刀架赫氏齿盘设计研究

针对伺服刀架的受力和结构形式特点,分析了伺服刀架在分别承受切向载荷、轴向载荷和径向载荷作用下的受力平衡和极限状态,推导了伺服刀架赫氏齿盘在切向载荷、轴向载荷和径向载荷作用下的承载能力公式,分析了伺服刀架的齿轮传动间隙对赫氏齿盘定位的影响。结合应用实例,介绍上述推导公式的使用,为实际工程应用提供设计依据。     

齿间摩擦力作用下的圆锥齿轮齿根弯曲疲劳强度的计算

传统的齿轮强度理论不计齿间摩擦力，认为齿间摩擦力对轮齿的强度影响很小。针对此观点，本文通过对一级减速直齿圆锥齿轮传动机构中主动轮受力情况进行全面地分析、综合地研究，推导出包含齿间摩擦力在内的主动轮齿根弯曲疲劳应力计算公式。研究结果表明，齿间摩擦力对圆锥齿轮齿根弯曲疲劳强度的影响不容忽视。     

变位斜齿轮和变位蜗轮注射模设计

电动汽车玻璃升降器中的塑料斜齿轮是一种变位齿轮,同样其中的蜗轮和蜗杆也是变位蜗轮和变位蜗杆。对于这种变位性质的斜齿轮和蜗轮注射模的设计,除了模具型腔的参数应该是变位性质之外,还需要考虑塑料收缩率的影响。最为重要的是模具脱模机构的设计,需要考虑注塑件脱模运动能产生与相应斜齿轮齿一致的螺旋运动。众所周知,塑料斜齿轮和蜗轮的直径都较小,因此,其因模数和齿数少的特点而具有变位性质。如此,该文对塑料变位斜齿轮和变位蜗轮注射模的设计便具有一种指导性的作用。     

大模数齿轮用材和强化工艺与齿弯曲疲劳强度

本文介绍了不同材质和强化工艺的大模数齿轮单齿弯曲疲劳强度试验结果,分析了齿根的弯曲疲劳特性及其影响因素,就进一步提高硬齿面齿轮轮齿的弯曲疲劳强度,提出建设性意见。     

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。