薄壁零件装夹方案设计与优化

针对薄壁零件刚性差,制造过程中在夹具夹紧力和切削力的作用下,容易产生加工变形,严重影响加工精度和表面质量等问题,分析和阐述了提高薄壁零件加工精度的装夹设计方法.研究了基于遗传算法和有限元方法的薄壁零件夹具布局和夹紧力的同步优化设计方法,以一壳体薄壁零件为例,进行了其夹具的装夹方案设计以及夹具布局和夹紧力的同步优化.结果表明该优化方法可以有效地降低由于装夹不当所引起的工件变形程度, 提高工件的加工精度.     

薄壁套磨削夹具

在组合机床加工中,经常遇到各种固定套、导套之类的薄壁套加工问题。尤其是精磨时,常因装卡变形,造成工件成批报废,给工作带来很大困难。我们制造了一种简单磨内孔的夹具(见图),它只有4种零件组成,解决了装夹变形问题。夹具体1装夹在磨床卡盘上,定位预紧螺栓2只能作轻微定位用,不能起夹紧作用,调好后要用背帽固     

真空吸附铣削夹具的设计及其应用

工件变形是影响薄板零件加工精度的主要问题。采用高速铣削加工可减小切削力、切削热、切削振动等产生的工件变形;利用真空吸附铣削夹具装夹工件,使其受到均匀分布的夹紧力,可大大减小因夹紧力造成的工件变形,提高零件的加工精度和表面粗糙度。在介绍真空吸附夹具结构设计与工作原理的基础上,重点阐述薄板零件高速铣削加工真空吸附夹具的设计要点及其应用。     

加工阀盖孔用钻镗两用夹具

生产中等批量阀盖孔时,传统方法是采用钻、镗两套夹具进行加工,增加了设计量,并且工件重新装夹有重复定位误差。针对这一问题,设计一套夹具就能完成以上两种夹具的工作,并采用UGNX70进行钻镗两用夹具的模拟装配。结果表明:该夹具既可以在钻床上使用,又可以在镗床上使用,只需更换钻套或镗套,工件无需重新装夹,降低了夹具设计成本,保证了工件的加工精度,提高了劳动生产率。     

精密阀芯径向孔钻床夹具设计

针对某精密阀芯外圆表面径向孔尺寸和位置精度高、加工质量不稳定的情况,设计一种采用V形槽反装定位、偏心轮装置快速夹紧的专用钻床夹具。详细分析了径向孔加工钻床夹具的定位和夹紧方案,计算出定位元件关键尺寸,阐述夹紧装置的原理和工作过程。经夹具精度分析与验算,发现所设计的夹具完全能满足精密阀芯径向钻孔的高精度要求。该夹具操作简便、适应性强、工件加工质量稳定,为机械行业销轴类零件高精度径向孔钻床夹具的设计提供了参考。     

门五金件孔槽数控加工的夹具设计方法研究

针对门五金件孔槽数控加工时多次装夹、多工序、多工位以及加工精度差、效率低等问题,从门五金件孔槽的结构特点及数控加工原理出发,分析门五金件孔槽数控加工机床夹具设计要求,提出一种新的门五金件孔槽数控加工夹具设计方法。该夹具系统能够实现木门全自动定位夹紧,且一次装夹可完成门五金件孔槽数控加工。该方法提高了加工精度、生产效率,对实现门五金件孔槽数控加工的规模化具有重要意义。     

一种联轴器加工用三爪卡盘设计

三爪卡盘是机床上用来夹紧工件的机械装置,其利用均布在卡盘体上的活动卡爪的径向移动,对工件进行夹紧和定位。但是在对联轴器装夹和加工时,由于联轴器的轴孔加工精度要高于外圆面的加工精度,因此采用三爪卡盘对联轴器的外圆面进行装夹不利于联轴器的高精度加工。为提高联轴器加工精度,提供一种结构简单、操作方便的联轴器加工用三爪卡盘,能够将联轴器稳定、精确的进行定位和固定,从而保证加工产品具有较高的加工精度。     

基于NX Nastran的缸体加工中心夹具夹紧杆的疲劳分析与优化设计

加工中心要在发动机缸体上加工出质量合格的型孔,缸体必须通过夹具可靠固定,夹具上各固定元件的有效性,直接影响工件的加工质量和设备利用率。利用计算机辅助设计软件UG与Nastran对缸体OP10-30数控加工中心频繁断裂的夹具夹紧杆进行应力分析和疲劳分析,并以此优化夹紧杆结构,延长夹紧杆使用寿命,减少工件因装夹不牢固造成加工震纹而报废的数量。     

发动机端盖类零件工艺装备设计与数控加工

传统端盖零件加工需要采用车床、钻床、铣床等多种设备,多次装夹存在重复定位误差、工作量较大等问题。针对端盖零件的加工问题,设计一套专用气动工艺装备,实现端盖零件一次装夹完成孔、螺纹的加工,该工艺装备采用气动夹紧装置,夹紧力可调,采用三点可调支撑调整工件平面度,通过径向定位装置准确定位工件初始角度,保证加工孔位置精度。通过NX UG 10.0软件编写数控加工工艺,利用立式加工中心完成端盖零件的数控加工。生产实践表明:该工艺装备实现了工件的快速装卸、大批量自动化生产,加工精度稳定且符合生产技术要求,生产效率明显提高,取得较好的经济效率。     

转向架轴箱专用机床及夹具设计

对转向架轴箱的加工方案进行分析,设计钻孔专用机床。为了实现转架轴箱体一次装夹完成4-12 mm孔的加工,设计一套液压专用自动夹具。实践证明:该夹具结构简单,操作方便,加工过程中实现了对工件的快速定位装夹,提高了生产效率。     

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.     

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。     

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.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.     

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.