板式制动器松闸扳手扁管成形工艺的仿真分析

为了对圆管在不同模具进给速度下的压扁成形情况进行总结和预测,基于ABAQUS有限元软件对板式制动器松闸扳手扁管成形过程进行数值模拟,通过将仿真结果与实验结果进行对比,验证了有限元模型的正确性,以此为基础,分析了不同模具进给速度以及采用低熔点合金芯轴对扁管成形效果的影响.研究结果表明:模具进给速度越大,管件中间直线部分向内凹陷的程度越大;添加低熔点合金芯轴后,可以减小圆管压扁成形后的截面畸变.通过分析得到了扁管成形的变形规律,为合理设计扁管成形工艺提供了有益的参考.     

模具材料优化选择与系统工程

以系统工程的观点对模具材料优化选择的决策进行了初步的探讨 ,并从抓主要矛盾解决问题的方法 ,就热作模具材料的优化选择提出了三类主要的决策方法 :绝大多数热作模具在高温重载下工作 ,模具寿命短 ,甚至一个工班要换几个模具 ,因此用失效抗力性能高的热作模具钢来制造此类模具 ;对锌、铅、锡等低熔点合金的压铸模或热挤压模 ,一般在 4 5 0℃下工作 ,服役条件相对好 ,可按产品批量大小选择 ,例如几十万件的可选合金结构钢 4 0Cr,30CrMnSi等 ,若批量上百万件的便选用标准热作模具钢 5CrNiMo ,H13,3Cr2W8V等 ;热冲裁模工作温度一般在 30 0℃以下 ,所有的热作模具钢都合用 ,因此着重从便于生产管理出发来选所用的钢材 .     

铸造镍基高温合金车削加工研究

在难加工材料镍基高温合金中,铸造镍基高温合金合金化尤为复杂。K403合金是铸造镍基高温合金中较为典型的代表。它是一种多组元、含量多、激活能高的高熔点复杂合金化材料,有较高的热强性,及热稳定性,其工作温度为850℃～950℃,广泛用于航空发动机零件。而且已成功地代替热作模具钢应用于热作模具,使模具寿命提高10～100倍,带来重大经济效益。在铸造镍基高温合金的扩大使用中,遇到的问题之一是很难切削加工。由于K403合金热强性高(800℃瞬时拉伸值σ_b=1029 MPa,σ_(0.2)=931 MPa),室温硬度高     

铜锡合金/高密度聚乙烯导电复合材料的制备与性能研究

主要研究以铜锡合金以及经偶联剂处理的铜锡合金作为导电填料通过球磨法添加到高密度聚乙烯基体中制备的复合材料的导电性能。DSC分析表明随着铜锡合金含量的增加,复合样品的熔点及结晶度均呈现上升的趋势,而经偶联剂处理后,复合样品的熔点及结晶度较未经偶联剂处理的样品有降低的趋势,且随着偶联剂含量的增加,样品的熔点及结晶度降低;导电性能测试结果表明随着铜锡合金含量的增加,复合样品具有更好的导电效果,且经过偶联剂处理的铜锡合金较未经偶联剂处理的铜锡合金具有更好的导电性能。     

WC/球墨铸铁复合材料的显微形貌与形成分析

对于采用的铸渗法制备的WC/球墨铸铁复合材料，通过电子探针与金相法分析合金元素的分布规律及显微组织形态，测试了其显微硬度，研究结果表明，表面复合层是由于在毛细作用下铁液被不断吸入合金层中，致使低熔点HT粉过热熔化而形成并与基体冶金结合，实际测试表明，该复合材料具有良好的抗磨损特性。     

铜基合金模具在拉延不锈钢饭盒中的应用

介绍了铜基合金模具在拉延不锈钢饭盒中的应用情况。结果表明:铜基合金模具拉延不锈钢饭盒,能有效地克服拉延时饭盒表面产生的划痕、拉破,产品的破损率由15％下降至0.1％左右。本文还对比分析了Cr12模具在拉延中的使用情况。     

铜基合金模具在深拉伸不锈钢器皿中的应用

本文简述了铁基合金模具拉制不锈钢器皿,易使器皿表面产生划痕、破损率高,难于抛光,模具的耐用度低等弊端;同时用铜基合金模具和铁基合金模具在深拉伸不锈钢水壶的生产中做了对此拉伸.拉伸统计的数据表明,使用铜基合金拉伸不锈钢器皿,对克服器皿表面划痕、减少破损率、提高模具耐用度、降低产品成本等均取得了明鲜效果.最后,作者又进行了一些粗浅的理论分析.     

微量混合稀土对共晶铝—硅活塞合金的变质作用

本文用混合稀土——铝中间合金作变质剂,研究了混合稀土对ZL108共晶铝—硅活塞合金变质前后的组织形貌及机械性能。指出,微量(0.03～0.09％)的混合稀土可使铸造铝活塞产生完全变质组织,且变质后共晶硅立体形貌呈颗粒状孤立分布,机械性能亦比钠变质时有较大提高。该变质剂熔点低、杂质少、加入工艺简便,无任何腐蚀及污染。     

电弧喷涂制造吸塑模具的研究

电弧喷涂是热喷涂方法的一种。电弧喷涂制造吸塑模具是这样的一种方法,首先选一木模、石膏模或吸塑制品实物作为主模,然后在其表面喷涂某种合金,当喷涂层达到要求的厚度以后,取掉主模,留下的型腔就可作为吸塑模具。 我校研制的模具是由两种合金涂层组成。模具的内表面衬有一层特种合金涂层,它保证     

低熔点光学玻璃表面加工工艺参数优化

为优化磁流变抛光对低熔点玻璃表面的加工工艺,文中利用磁流变抛光技术对低熔点玻璃进行抛光,分析了磁流变抛光中工艺参数对低熔点光学材料对表面粗糙度的影响,探讨低熔点玻璃通过冷加工的方法进行超光滑加工的效果.实验研究表明:在抛光液质量分数为15％、磨盘转速为35 r·min-1、抛光时间为50 min条件下,磁流变抛光对低熔...     

Effect of Ag and Ni on the melting point and solderability of SnSbCu solder alloys

To improve the properties of Sn10Sb8Cu solder alloy, two new solders(SnSbCuAg and SnSbCuNi)were formed by adding small amounts of Ag or Ni into the solder alloy. The results show that the melting point of the SnSbCuAg solder alloy decreases by 14.1℃ and the spreading area increases by 16.5% compared to the matrix solder.The melting point of the SnSbCuNi solder alloy decreases by 5.4℃ and the spreading area is slightly less than that of the matrix solder. Microstructure analysis shows that adding trace Ag makes the melting point decline due to the dispersed distribution of SnAg phase with low melting point. Adding trace Ni,Cu_6Sn_5 and (Cu,Ni)_6Sn_5 with polyhedron shape on the copper substrate can be easily seen in the SnSbCuNi solder alloy,which makes the viscosity of the melting solder increase and the spreading property of the solder decline.     

Synthesis of PEG-MAH crystalline polymer and its thickening traits to LPMC

A kind of PEG-MAH（maleic anhydride to modify polyethylene glycol） crystalline polymer whose melting point was approximately 64 ℃ was synthesized, and its thickening traits to LPMC were also investigated. The analysis of rheological properties indicates that the dosage and adding methods of crystalline polymer have a direct effect on the viscosity of LPMC, and that the thickening method of using melting dispersal and freezing is propitious to the thickening process of SMC. Additionally, it is also shown that SMC＇ s viscosity decreases along with the elevation of temperature, and that it reduces rapidly at the medium range of temperature, which is propitious to the dispersal of SMC in mould, and to its low pressure molding as well.     

Rheology in Processing of in Situ Composites of Polypropylene and Low Melting Poing Metals

The low melting point metallic tin powder or alloy of tin and lead was blended with polypropy-lene. A kind of in situ composite has been prepared. The variations of torque were studied when the composites were mixed in Haake torque rheogeniometer. By way of capillary extrusion, effects upon rheology of the in situ com-posites of the low melting point metals (LMPM) and coupling agent for their different variety and content, were investigated. From flow curves, the results indicate that in situ composites mixed with the LMPM are a kind of pseudoplastic fluid. If the LMPM were melted, the higher the content of the LMPM , the lower apparent viscosity of composites. Meanwhile, when the coupling agent is added into composites, the viscosity of composite will go up first and drop then. This shows that the LMPM have a promoter flow action on the polypropylene.     

气辅成型汽车把手注塑件抗拉强度

介绍了气辅成型的工艺过程和技术特点;分析了气辅成型工艺对聚合物熔体形态分布的影响。并对汽车把手件气辅成型制品和传统注塑成型制品的抗拉强度和抗弯强度进行了比较。结果表明:在相同注射压力、模具温度、试验材料的条件下,气辅制件的抗拉强度明显高于传统注塑制件的抗拉强度,两者的抗拉强度之比约为 1.7∶1;气辅成型制件的抗弯强度也比传统注塑制件有所提高。同时作者还分析了气辅制件强度提高的机理。     

Molecular dynamics simulation of Ni3Al melting

With the Voter-Chen version of embedded-atom model (EAM) potential and molecular dynamics, the melting of Ni3Al alloy was simulated by one-phase (conventional) and two-phase approaches. It is shown that the simulated melting point is dependent on the potential and the simulation method. The structures of the melts obtained by different simulation methods were analyzed by the pair correlation function, the coordination number, and the distribution of atom pair type (indexed by the Honeycutt-Andersen pair analysis technique). The results show that the structures are very similar.     

注射模CAE分析软件Z-MOLD的开发及应用

对注塑模CAE软件Z -MOLD的结构、功能设计、运行模式作了详细描述 .结合实际 ,着重论述利用注塑模CAE技术在计算机上快速模拟制品的熔接线和气穴位置 ,并根据产品的要求和模具设计准则 ,通过改变浇口位置来避免不合适的熔接线和气穴位置     

低熔点聚酯的热分析

通过对不同组分的改性共聚酯及其通过预结晶处理后进行DSC热分析,讨论了各类改性组分对共聚酯的玻璃化转变温度、结晶性能等方面的影响,由此推测改性组分在低熔点聚酯中所起的作用.以得到制备低熔点共聚酯的最佳配方等一些工艺参数.     

铝合金粉末注射成形工艺研究

用Ａｌ－Ｚｎ－Ｍｇ、Ａｌ－Ｆｅ－Ｓｉ合金粉末进行了注射成形工艺研究。所采用的粉末为自制急冷凝固（气体雾化）粉，所选用的粘结剂为热固性纤维素（含添加剂）．粉未与一定比例的粘结剂混合，得到均匀且具有一定流动性的混合料，采用不同的工艺参数注射成形。     

Superheating and melting behaviors of Ag clusters with Ni coating studied by molecular dynamics and experiments

Using molecular dynamics with embedded-atom-type interatomic potentials, we simulated the melting behavior of a spherical Ag3055 cluster coated with Ni. The semi-coherent Ag/Ni interface formed at low temperatures acts as an effective barrier against the surface melting and leads to a substantial superheating of the Ag cluster. The melting point was found to be about 100 K above the equilibrium melting point of the bulk Ag crystal (1230 K?15 K) and about 290 K above that (1040 K) of the free Ag3055 cluster. A superheating of 70 K was observed in the high-temperature differential scanning calorimetry measurement for Ag particles with a mean size of 30 nm embedded in Ni matrix prepared by means of melt-spinning. Melting is initiated locally at the defective interfacial area and then propagates inwards, suggesting a heterogeneously nucleated melting event at the Ag/Ni interface.     

铝合金管坯低熔点塑性介质挤胀成形力学特征

为了揭示管坯低熔点塑性介质挤胀成形力学特征,对铝合金管坯低熔点塑性介质挤胀成形工艺过程进行了研究.将低熔点塑性介质作为传力介质填加到管坯的内腔里,两个水平冲头在挤压管坯的同时挤压管坯内的塑性介质,使其在受挤压过程中自行封闭,自行产生高压,在管坯两端轴向挤压力的共同作用下,最终将管坯挤胀成形为空心构件.研究结果表明:低熔点塑性介质挤胀成形时管坯和塑性介质两种材料同时发生塑性变形,管坯的变形流动是塑性介质的内压和冲头轴向挤压共同作用的结果,采用该工艺可以成形各种异型截面的空心构件.