微挤压模具设计

零件微型化对微型零件的加工带来的影响是多方面的,影响范围主要包括4个方面:材料、工艺、工模具和设备。模具设计的精度的高低能够影响成形过程中成形件的质量。为了进行微单杯挤压试验,从试验的实际需求出发,参照宏观设计方法设计了一套精度较高的微挤压模具及温度控制装置,用微挤压模具挤出了表面质量及尺寸较好的微型单杯状零件。     

浅孔杯形件挤压工艺研究及模具涂层应用

以某浅孔杯形件为研究对象,依据塑性成形理论,设计了4种挤压成形工艺,即上冲头反挤压、浮动凹模上冲头反挤压、上冲头正挤压以及浮动凹模上冲头正挤压工艺,采用DEFORM软件分析了4种挤压成形工艺下杯形件的成形质量及各主冲头的磨损情况,并确定了成形工艺。为降低主冲头磨损,研究了在TiN、TiCN、TiN-TiCN涂层下各主冲头的磨损情况,并确定了合理的镀层材料。通过正交试验法,研究了冲头圆角半径、摩擦因数、冲压速度、涂层厚度对冲头表面磨损深度的影响,并确定了最佳工艺参数。结果表明:在保证零件质量的条件下,采用浮动凹模上冲头正挤压工艺,冲头涂层材料选择TiN-TiCN复合涂层,工艺参数选择涂层厚度为4μm、摩擦因数为0.08、冲压速度为10 mm·s~(-1)和冲头圆角半径为6 mm时,主冲头完成单次挤压后的磨损量较小。     

磁控排气管挤压成形的分析与参数优化

根据挤压成形理论,分析、制定了磁控排气管挤压成形工艺,采用Deform-3D软件对零件的成形过程进行模拟,应用正交模拟试验和回归试验以及工程试验研究相结合的方法,对微波炉磁控排气管金属冷挤压成形规律进行了研究,对工艺参数进行了优化.确定了模具结构参数的优化组合为:凸模内圆角r1=0.8 mm,凸模外圆角r2=0.8mm,凹模内圆角r3=0.2 mm,凹模外圆角r4=0.8mm.工艺参数的优化方案为:坯料直管长度x1=30nm,坯料锥角x2=120°,摩擦因子x3=0.1,挤压速度x4=180 mm·s-1.实现了薄壁空心杯杆件的复合挤压成形.     

微成形热挤压试验及模具设计

介绍了采用半固态ZL101铝合金进行挤压成形微型齿轮的试验研究,设计了挤压模具和加热及温控系统.试验结果表明,挤压过程中的坯料温度对零件质量产生重要影响,它决定了半固态合金的触变特性,合适的半固态加工技术可以成形微型零件.     

犁削挤压角对切削性能影响的模拟研究

将直径为6 mm的微型铜管简化为厚度0.4 mm的铜板,应用DEFORM-3D软件对微沟槽犁削-挤压成形过程进行模拟,在模拟过程中只有刀具挤压角单一参数变化(45°、60°、90°),通过分析在3种不同挤压角刀具成形下的铜板翅结构、应力和应变分布图,得出60°挤压角刀具犁削-挤压切削效果最佳。     

微挤压成形系统的设计与实现

针对微挤压成形工艺要求,设计开发了一种微挤压成形系统,该系统装置采用压电陶瓷为驱动器,以实现成形速度的精确控制;利用压簧-楔块机构实现自动进给,减少了人工操作步骤;通过计算机控制系统与传感器,实现对微挤压成形过程的实时控制及数据采集。在室温条件下,使用该成形系统对铅丝坯料进行微挤压实验研究,结果表明,成形装置受力形变对挤压结果产生的影响可以通过适当的预紧力得到改善,从而成形出轮廓清晰的微型齿轮,验证了该研究方案的可行性,为后续的微型金属零件成形研究提供技术依据。     

螺塞复合挤压的材料分配规律研究

针对螺塞零件复合挤压时的材料分配规律进行研究,推导出圆杯正六边形杆复合挤压的材料分配公式,提出材料分流层的形状是旋转抛物面。应用Deform软件对螺塞零件的挤压成形进行数值模拟,得到成形应力图和挤压力行程曲线,研究发现,螺塞的成形过程实际上分为2个阶段:复合挤压和反挤压。最终进行产品试制,试验结果表明:正反挤两个出口高度的实际数值和理论值吻合较好。     

整体式自润滑关节轴承挤压成形数值模拟

为实现对整体式自润滑关节轴承外圈挤压成形工艺的精确控制,提高外圈成形质量,改善产品密合度,减少自润滑衬垫的过压状态,以GE15DE1TK-HVS0型自润滑关节轴承为研究对象,采用有限元数值模拟技术对其外圈挤压成形工艺过程进行模拟分析,确定了挤压力及挤压行程,估算了外圈的成形状态及密合度。以模拟挤压力及挤压行程结果为依据,对该型轴承进行样品加工及密合度检测,并将检测结果与模拟结果进行对比,以判断数值模拟方法的可靠性。对比结果表明,数值模拟与工艺试验之间的误差为2. 4%～7. 3%,两者具有较好的一致性,说明有限元数值模拟技术可以对整体式自润滑关节轴承挤压工艺参数及外圈的成形效果进行有效预测。     

微型零件半固态反挤压数据采集装置的设计

介绍了微型零件半固态反挤压成形工艺特点,设计了一套微型零件半固态反挤压数据采集装置,并对其工作原理进行了阐述。微型零件半固态反挤压数据采集装置实现了凸模载荷和位移数据的实时采集和温度的精确控制,经使用该装置对ZL101铝合金坯料进行半固态反挤压试验研究,验证了该数据采集装置的可行性。     

联接轴的冷挤压毛坯形状及模具结构

通过对联轴器中联接轴的结构分析 ,提出了杯 -杆型零件成形时存在的问题。当杆的断面收缩率比杯形部分断面收缩率大得较多时 ,不适合直接用复合挤压成形。为了用复合挤压一次成形 ,提出了一种比较合适的毛坯形状 ,为类似零件的冷挤压成形探索了一条行之有效的途径。     

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.     

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.     

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.