精密镗滚复合刀具设计及切削用量确定

国内外对精密液压缸缸体的深孔加工十分重视。为提高被加工孔轴线的直线度、降低废品率,深入剖析了深孔镗滚加工中刀具的设计问题,提出优化刀具几何参数、合理确定切削用量、完善刀具支承结构等措施,改善了加工质量,获得了较为满意的加工效果。     

热轧管深孔镗滚加工的走偏问题剖析与结构优化

为控制孔轴线的偏斜,提高孔轴线的直线度精度,降低废品率,剖析了深孔镗滚加工中刀具走偏的根本原因,提出了合理设置刀具参数、提高刀具装配精度和支承刚度、优化支承套结构等措施,从而改善了加工质量,获得了较为满意的结果。     

一种缸筒类零件内孔的加工方法

介绍了一种缸筒内孔加工方法,它在精镗内孔完成后,再对缸筒内孔进行滚压,其粗镗、精镗和滚压均在采用普通车床改装制成的专用机床上进行。这种缸筒内孔的加工方法与现有技术相比,可解决现有缸筒内孔废品率高、加工成本高的问题。     

基于模态试验的两种减振镗杆动态特性测试

深孔加工中刀具颤振是影响加工效率、加工精度和表面质量的主要因素,采用具有减振功能的镗杆是解决深孔加工颤振的有效技术途径.针对两种不同类型的减振镗杆,采用模态试验的方法测试其动态特性,给出其模态参数和固有振型,为大长径比深孔加工用减振镗杆的研制与使用提供参考.     

薄壁长筒零件深孔镗削工艺与数控组合机床设计

文章对薄壁长筒类零件内孔镗削方法进行了分析,并设计了深孔镗削数控组合机床.同时机床的布局及主轴箱、弹簧夹头、深孔镗刀等关键部件进行了详细介绍.该机床的成功研制,解决了薄壁长筒零件深孔加工的难题,通过更换数控加工程序,更换夹头及刀具,调整液压中心架和导向架的轴向位置,该机床可以实现不同尺寸薄壁长筒类零件的内孔加工,运行效果良好.     

T2120深孔钻镗床的受油器的改进

我厂购进的 T2120深孔钻镗床,用来加工液压支柱的主要零件油缸内孔,其原来的传统工序是粗镗内孔、精镗内孔、珩磨内孔加工成形。为了改变传统工艺,以适应油缸深孔滚压新工艺的要求,我们将厂购进的 T2120深孔钻镗床的受油器结构进行了改进。改进后,通过一年多生产实践验证,保证了产品质量,降低了材料消耗,提高了生产率,从而取得了明显     

印刷机胶筒的旋压加工

一、胶筒的旋压加工旋压胶筒的工艺流程印刷机胶筒的零件图如图1.从图可以看出,胶筒只对内孔尺寸精度、表面粗糙度要求较高.选用旋压加工的工艺流程为:下料、车外圆、初镗内孔、半精镗内孔、旋压、平两端定长短.旋压坯料图如图2所示.旋压坯料的晶粒度若大于四级将影响材料的可旋性,可能产生旋压裂纹等问题.所以,要求材料进行正     

筒体法兰孔焊接坡口加工专机的开发

对筒体法兰焊接坡口加工的专用机床进行研究,就筒体加工马鞍形焊接坡口孔的特点,对坡口曲 面进行了深入分析,设计了一种适合筒体加工平面坡口及马鞍形焊接坡口的镗削加工装置.为筒体焊接法兰时使用自动化焊接设备提供了较理想的坡口结构.     

在车床上用枪钻加工镗杆H7孔

在车床上用枪钻加工镗杆Ｈ７孔大连机床厂董培生主题词：枪钻，深孔加工，车床改装镗杆是组合机床零件的关键件。由于镗杆内孔细长，精度要求较高，目前在我厂的现有加工设备中不具备加工镗杆Ｈ７孔的能力。为此，我们对我厂的３米Ｃ６２０车床和ＣＤ６２５６Ｂ车床进行了...     

关于细长镗杆的改进实践

我厂自行设计制造的三台钢件深孔组合镗床,在使用中因镗杆刚性差,加工出来的零件精度达不到要求。后来经过反复试验,改进了镗杆,终于使镗孔质量达到并超过了设计要求。 下面介绍一个细长镗杆改进前后的情况: 图1为被加工零件工序图,孔φ58_( 0.20)~( 0.25)为本工序要加工的孔,全长282毫米,表面光洁度5。图2为原设计镗杆,在加工镗杆时,因受设备限制,没有按图纸要求调质处理。结果,在使用中出现镗杆颤动,镗削出来的孔表面的刀纹呈波浪状,光洁度3。同时合金刀头易     

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。