发动机齿轮室盖液压自动夹具设计

齿轮室盖零件是典型的形状复杂、加工部位众多、形位精度要求高的铝合金薄壁箱壳类零件,其数控加工工艺及工装设计是复杂薄壁箱壳类零件数控加工的典型案例。通过对某型号发动机齿轮室盖零件结构与尺寸精度要求的分析,编制符合企业加工能力和要求的数控加工工艺路线。针对薄壁装夹刚性差、加工部位多与走刀路径干涉问题,合理选择装夹点位置,布置浮动支撑,设计相应液压自动夹具。该套数控加工工艺及工装已应用于实践,为其他同类型零件加工提供借鉴。     

工件定位销孔的刚性加工

在内燃机机体、缸盖、齿轮室等工件的加工生产中 ,定位销孔是其他工序的基础 ,也是保证装配后整机性能的关键。所以其位置精度要求很高 ,一般都要求在 0 .0 3mm以内。因此定位销孔的精度成为影响内燃机质量的一个重要因素。以我公司为例 ,以前的定位销孔加工为导套式加工 ,定位销孔的精度受夹具孔座标的误差 ,刀具、导套、衬套、夹具立臂间的配合误差 ,刀具本身的跳动误差 ,夹具的夹紧变形 ,滑台的运动刚度等因素的影响 ,很难保证加工精度 ,机体、缸盖的定位销孔位置精度在 0 .0 8mm左右 ,齿轮室的定位销孔位置精度在 0 .10mm左右。为解决…     

差速齿轮进给机构的组合镗孔装置

我厂设计制造的一种差速齿轮进给机构的组合镗孔装置(图1),具有结构简单、使用方便、制造周期短等优点。现主要用于加工195型柴油机缸体、连杆和正时齿轮室盖等零件。经过两年多的使用实践证明效果良好,镗孔精度可达二级,光洁度可达6。这种装置可以用来进行各种零件的孔加工,尤其适合于小批量零件的加工。     

小模数齿轮注射模设计

<正> 1 塑件结构分析图1是计算机打印机中传动部分的小塑料齿轮,材料为聚甲醛,尺寸小,精度要求高,齿轮径向跳动要求不超过0.031mm;齿轮外径相对于φ13mm的端面跳动不超过0.015mm;2.2_0~(+0.1)mm 槽相对于φ8~_0(+0.022)mm 表面的对称度不超过0.04mm。且要求塑件表面光洁,无流痕,无飞边。如何保证这些要求是该模具设计的关键。     

钼丝损耗分级补偿

钼丝损耗引起的加工精度误差,会导致凹凸模配合间隙减小,对于材料薄,配合间隙小的模具甚至无法配合。怎样延长钼丝使用寿命呢?我们的做法是:钼丝损耗分级补偿。钼丝损耗分级补偿就是是先根据钼丝损耗的趋势,将钼丝直径分成若干个等级,编程人员按钼丝的不同直径,结合模具间隙大小,一次给出△R的值,操作者在加工前用千分尺测量钼丝直径(多点测量取平均值),对照工艺要求置入相应的△R值进行加工。我厂使用的钼丝规格为φ0.1mm,以0.005mm为数量级,分为+φ0.1mm、+φ0.095mm、φ0.090mm、φ0.085mm(根据需要还可增加φ0.080mm、φ0.075mm)四个等级。利用这种方法,在钼丝损耗的不同程度下都能加工出合格的零件。如加工较高精度的多型腔凹模时,还可以在下一型腔加工前重新测量钼丝直径,按钼丝损耗的不同程度,修改△R值,再继续进行加工。     

线切割以外圆定位的简便加工方法

我在加工各种粉末冶金模、胶木模和塑料模的过程中,设计了一个简便的夹具,从而使定位误差缩小到最低限度(只受工件的不圓度和线切割机床的精度影响),保证了工件外形与型腔的同心度及垂直度。并能加工不同外径的工件,适用范围大(从φ80～90mm到φ1～φ2mm都行),一般都能自制。     

油泵壳体压铸模设计

<正> 1 产品结构分析 油泵壳体是汽车柴油发动机高压喷油泵中的重要零件之一。壳体的外形复杂,四周孔穴较多。尺寸精度和表面粗糙度要求较高。转子室以及各油路孔道均要求进行气密性试验,在0.4MPa的压力下不允许有渗漏现象。最大孔径φ66.5mm,与φ23mm、φ29.5mm的同轴度公差0.05mm。壳体材料     

国外电火花成形加工之最

最高成形加工生产率:10000mm~3/min最高成形加工(小孔)光洁度:▽12(0.1μRmax)最高形腔加工精度±0.01mm最大平动头电极承重:150公斤最大机床主轴电极承重:30000公斤最多电源回路数量:96回路(500安)最小加工孔直径:15μ最大加工小孔深度与直径之比:100以上(孔深30mm,孔径φ0.3mm)最大的小孔加工速度:30mm/min(工件不锈钢,直径φ0.5mm)最高的小孔加工精度不圆度:0.5μ,直径±1μ最大电源脉冲电流:1000安(平均)     

微型冲床

为了满足多品种少批量、高精度冲压生产的需要,日本湖东制作研制成功附有电视监控的微型冲床,这种冲床适用于不锈钢、铝合金、软钢系薄板材料的冲压。为了保证加工精度,使用了电视摄象和视监控,把加工部分的图形放大7～10倍,以投影显示冲压加工状态。该冲床加工精度可达到0.05mm以内(自动定位精度为0.02mm以内)的高水准,掉换凸、凹模也非常方便。该冲床额定冲压力约1吨,可冲压φ7.5×0.6(mm)的不锈钢板,φ18×2(mm)的铝     

柴油机机体铸造裂纹及表面缩松缺陷的防止

1　机体铸件结构及铸造工艺概况我公司生产的 R175A柴油机机体结构见图 1,材质为 HT2 0 0 ,最大外形尺寸 2 86× 2 73× 196 (mm) ,毛坯质量 2 8kg,铸件主要壁厚仅为 5mm,最大壁厚 2 5mm,是典型的薄壁箱型结构。图 1　 R175 A机体毛坯筒图1 -曲轴室 ;2 -齿轮室 ;3-齿盖面 ;4-轴承座孔 ;5-底脚板 ;6-缸盖面机体采用无冒口铸造工艺铸造 ,齿轮室朝下 ,底脚板中心对称分型 ,每型两件 ,流水线机器造型 ,手工制芯 ;铸件齿轮室坭芯采用粘土砂芯 ,曲轴室坭芯采用渣油砂芯 ;浇注系统采用 3道扁梯型内浇口 ,于铸件分型面底脚板处进铁水。浇注温度 >…     

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.     

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.