工艺参数对连续挤压铜/铝复合接触线成形的数值模拟研究

针对铜铝无法复合成形和铜铝结合面不紧密等问题,采用Deform-3D有限元软件,模拟了铜铝复合接触线连续挤压包覆成形过程,研究了成形过程不同模芯端部导流角、复合变形区长度、坯料与模具表面状态和挤压轮转速对铜铝复合接触线包覆质量的影响.研究结果表明:模芯端部导流角度取45°~30°,复合变形区长度L取5 mm,铜铝结合紧密度高,包覆效果好;提高铜线与铝线之间的摩擦,降低模具与铜线之间的摩擦,有利于实现铜铝流动的同步性;适当提高挤压轮转速有利于铜铝结合面紧密度的提高.在TLJ340连续挤压机上进行了铜铝复合试验,试验结果与数值模拟结果相吻合,成功生产出质量合格的铜铝复合接触线产品.     

高强钢板热冲压成形热力耦合数值模拟

为研究高强钢板的热冲压成形性,采用ABAQUS软件对高温下22MnB5高强钢板沟槽形件冲压成形进行了数值模拟研究.建立了基于热力耦合的弹塑性有限元模型和热成形下的材料模型,通过对沟槽形件热成形进行数值模拟,考察了压边力、模具间隙和凹模圆角半径等工艺参数对热成形时温度分布和回弹的影响,给出了热成形中产生回弹的机理,确定了合适的工艺参数,通过热成形试验验证了数值结果的可靠性.     

连续变截面直接挤压成形技术研究

实现晶粒细化的传统塑性加工工艺所需工序多且要求较高,为了解决这些问题,本文提出了一种能够实现金属材料制备及成形一体化的挤压成形新工艺——连续变截面直接挤压成形技术.对不同工艺条件的连续变截面挤压成形过程的数值模拟研究表明:当模角由90°增大至140°时,塑性区范围明显扩大,金属流动均匀性随之提高;模口处轴向拉应力数值减小了20%,降低了表面产生开裂的可能性;模角为90°时变截面型腔处存在死区缺陷,且流线折叠倾向较严重,模角为140°时成形过程中坯料与型腔间易出现空隙.分析认为,本文条件下模角为120°的情况比较理想.     

基于数值模拟的极限凸翻边研究

为了提高薄板冲压成形零件的疲劳寿命,将半手工操作的落锤压制(冲压)方法改为高压橡皮成形(静压)方法而进行的工艺研究试验;同时,为高压橡皮半模成形确定最合适的工艺过程设计(CAPP)进行计算机仿真.运用自行开发的静-动力有限元软件分析橡皮成形凸模圆角半径和板料厚度对凸翻边成形极限的影响,并建立预测橡皮成形凸翻边成败的t极限翻边高度Hmax、凸模圆角半径r凸、板料厚度t的关系曲面.根据所得数值模拟的极限凸翻边高度Hmax模与7.7万吨橡皮囊液压机的试验结果Hmax实的对比,吻合很好;数值模拟将凸翻边起皱-压贴的真实过程描述得很清楚,而理论计算结果与物理实验结果有一定的差值.     

基于 Deform-3D 的车用下轴套零件冷挤压模具结构优化设计

目的分析挤压成形中车用下轴套零件成形表面出现的折叠缺陷,优化挤压上凹模的底部出口斜度、下凹模的入口斜度和挤压深度等主要成形工艺参数。方法采用DEFORM-3D软件,对汽车下轴套零件的冷挤压成形工艺进行了系统的有限元数值模拟试验。结果挤压成形模具结构设计不合理,导致在成形过程中模具分型面处金属出现汇流并形成折叠。结论通过优化挤压模具结构,使金属成形良好,无折叠缺陷出现,最终获得了较为合理的冷挤压模具结构。     

某型号十字轴精密成形工艺分析

目的研究十字轴闭塞式单向温挤压成形的可行性。方法根据十字轴的结构特点,确定了成形方案,并利用有限元技术对成形过程进行了数值模拟分析,然后结合物理实验对工艺可行性进行了验证。结果有限元分析和试验结果相吻合,锻件成形效果较好,没有出现充不满、折叠缺陷。结论采用闭塞式单向温挤压成形工艺,获得了满足尺寸要求的十字轴锻件,成形过程稳定可靠,成形工艺可行。     

十字头锻件挤压成形的研充

本文介绍了汽车万向节十字头分模模缎的实验与研究工作。着重阐述了十字头锻件在可分凹模中挤压成形时金属的流动规律;分析了模具形状、尺寸和其它工艺参数对缎件成形的影响;探求了挤压力及合模力的计算方法,并与实测数据作了对比。以期为进一步研究和推广这一先进工艺提供经验和科学依据。     

基于 AHP 与灰色系统理论的隔热件成形回弹控制优化

目的汽车隔热件的冲压成形过程比较复杂,成形工艺参数较多,实际生产难以准确地建立起工艺参数与质量目标之间的联系,研究工艺参数对成形质量及回弹的影响为实际生产提供指导必要而有意义。方法对模具间隙、凹模圆角半径、摩擦因数等影响回弹的因素进行正交试验,设计了试验方案,获得了成形零件的回弹数据;结合层次分析理论(APH)计算了成形工艺参数对多质量目标的权重,最后利用灰色系统理论,计算出了成形质量相对目标函数的关联度,再进行进一步计算获得各成形工艺参数的平均关联度,将优化后的工艺参数应用于有限元仿真与实验验证。结果通过层次分析理论和灰色系统理论对成形工艺参数进行优化,获得了优化工艺参数组合,隔热件成形质量明显提高,回弹量控制在较小范围内。结论当模具间隙为0.805 mm、凹模圆角半径为12 mm、摩擦因数为0.125时,回弹前后距离差Δd=0.918 mm、回弹前后夹角差Δα=0.340°,回弹得到有效控制。     

凸模结构对大截面带筋方筒件挤压力的影响研究

目的 解决大截面铝合金带筋方筒构件在反挤压过程中成形力大的难题,实现在3 000 t压力机下成功制备内孔为665 mm×665 mm的大截面带筋方筒形构件。方法 提出了一种使用新型棱台凸模结构代替平凸模结构的方法,用主应力法得出了棱台凸模结构与平凸模结构的挤压力计算公式,对比分析了2种凸模结构反挤压成形力的大小,并用DEFORM有限元软件模拟分析了不同结构参数下的棱台凸模反挤压过程,最终进行工程试制,验证了反挤压工艺的可行性。结果 通过主应力法得出了方筒形件的变形力计算公式,得出棱台凸模结构反挤压成形力小于平凸模结构反挤压成形力,经模拟分析得出在反挤压过程中棱台凸模结构的最优结构参数为棱台斜角15°、棱台高度40 mm,并在3 000 t压力机上成功制得内孔为665 mm×665 mm的大截面带筋方筒形构件。结论 通过数值模拟分析可知,与采用平凸模结构相比,采用棱台凸模结构时的反挤压成形力降低了约13%,同时减少了挤压变形过程中的金属流动“死区”。经实验验证,在3 000 t压力机上成形了内孔为665 mm×665 mm的大截面带筋方筒形构件,实现了省力挤压。     

基于数值模拟的管材平面弯曲成形几何加工精度规律

目的 建立高精度的有限元仿真模型可以有效地指导实际加工生产,在减少实验成本及结构件制造开发周期的同时提高成形效率。提高数值模拟中金属管材平面弯曲成形的几何加工精度,同时探究关键工艺参数对几何精度的影响规律,确定最佳工艺参数组合。方法 以管材平面弯曲成形构件为研究对象,建立了基于自由弯曲技术的管材弯曲成形有限元仿真模型,并通过实际加工实验验证了仿真精度,随后针对仿真模型的几何误差进行了参数补偿。将使用较高精度的仿真模型模拟得到的数据作为数据来源,研究关键工艺参数对仿真成形几何精度的影响机制,采用熵值法确定最佳工艺参数组合。结果 通过实际成形实验对比分析,在不同成形条件下,有限元仿真结果与实际加工结果高度吻合,两者之间的加工误差不超过2%,针对规格为32 mm×2 mm的20号碳钢管材,当轴向推进速度为5 mm/s,管材与弯曲模间隙值为0.25 mm时加工精度最高。结论 优化改进后的有限元仿真模型具有较高的几何成形精度,可有效指导实际成形工艺参数的优化工作。     

Effect of Gap Size on Coating Extrusion of Pb-GF Composite Wire by Theoretical Calculation and Experimental Investigation

1.IntroductionContinuous fiber composite wire has been of great im-portance for its high market potential in recent decade.Lead-clad glass fiber(Pb-GF)composite wire can bewidely used in various fields,including grid plates in bat-teries for electric vehicles(EVs)and hybrid electric vehi-cles(HEVs),radiation protective grid plates and soundinsulation,due to its high tensile strength,good resis-tance to acid corrosion,sound electric conductivity,highdamping and radiation protection of lead[1…     

Improved adhesion between nickel–titanium SMA and polymer matrix via acid treatment and nano-silica particles coating

Shape memory alloy (SMA) composites are the desirable candidate for smart materials that used in intelligent structures. However, the overall mechanical performance of SMA composites depends immensely on the quality of the interaction between SMA and polymer matrix. Therefore, it is necessary to find out an approach to enhance the interfacial property of this composite. In this paper, we modified nickel–titanium SMA wire with nano-silica particles before and after acid treatment. The modification effect on the interfacial strength between SMA and epoxy resin was evaluated. Contact angle analysis, scanning electron microscopy (SEM) observation, and single fiber pull-out test were carried out. The bonding characteristics between modified wire and liquid/cured resin were investigated. We then embedded SMA wire into woven glass fabric/epoxy composite laminates, and manufactured this hybrid composites via vacuum assisted resin transfer molding processing. Three-point-bending test of the hybrid composites was performed to validate the modification effect. Fiber pull-out experiment demonstrates that the interfacial shear strength increases by 6.48% by nano-silica particles coating, while it increases by 52.21% after 8 h acid treatment and nano-silica particles coating simultaneously. For hybrid composites, flexural strength of the two specimens increases by 19.8 and 48.2%, respectively. In SEM observation, we observed large debonding region in unmodified composites, while interfacial adhesion between modified wire and epoxy keeps strong after flexural damage.     

碳纳米纤维纸-玻纤/环氧复合材料对风力发电叶片的影响

针对风力发电叶片在多风沙环境下的固体粒子冲蚀磨损行为, 研究了风力发电叶片专用环氧树脂(EPIKOTE^TM RIM 135、EPIKURE^TM RIM H 137)、传统玻纤增强环氧复合材料和新型碳纳米纤维纸-玻纤/环氧复合材料的固体粒子冲蚀磨损行为, 并测试了不同材料的玻璃化转变温度, 进而对比分析了其对冲蚀磨损的影响; 针对风力发电叶片在寒冷环境下表面容易结冰的现象, 研究了上述三种材料表面的疏水性能, 并测试了它们对水的接触角大小。结果表明: 碳纳米纤维纸-玻纤/环氧复合材料具有良好的界面结合, 且碳纳米纤维纸的引入提高了碳纳米纤维纸-玻纤/环氧复合材料的玻璃化转变温度(从55 ℃提高到63 ℃), 从而改善了其耐固体粒子冲蚀磨损性能; 同时, 碳纳米纤维纸的加入改善了碳纳米纤维纸-玻纤/环氧复合材料的表面疏水性能(接触角从104°提高到131°)。     

Tensile-force-induced delamination of polymeric coatings in tightly jacketed double-coated optical fibers

To maintain the mechanical strength, the glass fiber of optical fibers is coated by polymeric materials during the fabrication process. However, when the external tensile-force-induced shear stress at the interface of the glass fiber and primary coating is larger than its adhesive stress, the polymeric coatings will be delaminated from the glass fiber and optical fiber will lose its mechanical strength. In this article, the tensile-force-induced delamination of polymeric coatings in tightly jacketed double-coated optical fibers is investigated. To minimize the coating's delamination, the tensile-force-induced shear stress at the interface of the glass fiber and primary coating should be reduced. The method to minimize such a shear stress is to select suitable polymeric coatings as follows. The Poisson's ratio of the primary coating and the Young's moduli of the secondary coating and jacket should be increased, but the Young's modulus of the primary coating and thickness of the secondary coating should be decreased. On the other hand, the thickness of the primary coating has an optimal value. The selection of the adhesive shear stress between the glass fiber and primary coating in the minimization of the coating's delamination is also discussed.     

密度法测定有机硅玻纤复合材料的树脂含量

灼烧法是玻纤复合材料树脂含量测定的常用方法,对于有机硅树脂类的玻纤复合材料,不能通过灼烧完全去除掉树脂基,因此灼烧法不适用.密度法是通过测定玻纤、样品和树脂的密度计算出其树脂含量.采用密度法和灼烧法对同一批玻纤复合材料进行树脂含量的测定,通过比较两种方法的测试结果以及不确定度可以得到:密度法的树脂含量为40.8％,灼烧...     

基于弯曲性能的黄麻纤维增强聚氨酯复合材料工艺参数研究

针对黄麻纤维增强聚氨酯复合材料的弯曲性能,采用正交实验的方法,研究了纤维质量分数、纤维长度、成型压力和纤维表面处理方法四个因素对其的影响.通过对实验结果进行方差分析和极差分析,对工艺参数进行了优化.研究结果表明:纤维表面处理方法为复合处理、纤维质量分数为15%、成型压力为80t、纤维长度为25mm时,复合材料弯曲性能达到最优.该结果与玻纤、碳纤增强聚氨酯复合材料制品作相应的对比,并为提高实际生产的制品质量提供了理论依据.     

A Novel Manufacturing Route for Automobile Parts through Two-Wire-Arc Thermal Spray Process

The present work deals with a novel manufacturing route that can be used to fabricate automobile sheet parts such as bonnet/bumper by metal alloy coating through two-wire-arc thermal spray (TWATS) process. Later the coating is supported with fiber through cladding process and becomes a freestanding composite coating. The coating has a metallic look and is free from oxidation. This novel manufacturing process is rapid and customized. A case study, where aluminum alloy wire was used to produce freestanding coating, was performed by response surface method optimization of the two-wire-arc spray process factors: the voltage, current, spray distance, gas pressure, and selection of mold/substrate material that was used to fabricate automobile bonnet. Initial experiments were performed on the four different substrates materials, viz., steel, aluminum, ceramic, and graphite; the graphite substrate showed some promising results and was selected to run the experimental array to optimize the process parameters. Spray distance more than 150 mm, voltage 30 V, current 250 A, and primary atomizing gas (nitrogen) pressure 100 psi (0.689 MPa) may be used. The freestanding aluminum coating was evaluated analyzing its performance, in terms of desirable microstructure and mechanical properties.     

连续玻纤/PE增强复合带弹性参数计算方法

为研究连续玻纤/PE增强复合带的弹性性能,建立了连续玻纤/PE增强复合带模型,并对其材料及结构提出了基本假设,在此基础上采用理论公式法求解了复合带的弹性参数.建立了复合带在单向拉伸状态下的有限元模型,对玻纤与PE进行了位移耦合处理,求得了复合带沿玻纤长度方向的弹性模量,该结果与理论结果吻合很好.通过拉伸实验获得了复合带玻纤长度方向与带宽方向的弹性模量,带宽方向的弹性模量与理论结果吻合;而在玻纤长度方向上,由于加工工艺、材料状态等与假设条件之间的偏差,以及实验测试过程中存在的误差,其弹性模量与理论解、数值解相比偏低.     

Mathematical modeling and analysis of WEDM machining parameters of nickel-based super alloy using response surface methodology

Inconel 625 is one of the most versatile nickel-based super alloy used in the aerospace, automobile, chemical processing, oil refining, marine, waste treatment, pulp and paper, and power industries. Wire electrical discharge machining (WEDM) is the process considered in the present text for machining of Inconel 625 as it can provide an effective solution for machining ultra-hard, high-strength and temperature-resistant materials and alloys, overcoming the constraints of the conventional processes. The present work is mainly focused on the analysis and optimization of the WEDM process parameters of Inconel 625. The four machining parameters, that is, pulse on time, pulse off time, spark gap voltage and wire feed have been varied to investigate their effects on three output responses, such as cutting speed, gap current, and surface roughness. Response surface methodology was used to develop the experimental models. The parametric analysis-based results revealed that pulse on time and pulse off time were significant, spark gap voltage is the least significant, and wire feed as a single factor is insignificant. Multi-objective optimization technique was employed using desirability approach to obtain the optimal parameters setting. Furthermore, surface topography in terms of machining parameters revealed that pulse on time and pulse off time significantly deteriorate the surface of the machined samples, which produce the deeper, wider overlapping craters and globules of debris.     

玻璃纤维/环氧树脂复合材料与镀层界面的Ni颗粒强化工艺

针对玻璃纤维/环氧树脂复合材料与镀层结合界面强度低的问题,基于复合材料/镀层间的机械互锁原理及传统塑料基体化学镀工艺,提出通过增强颗粒的桥接作用,增加含有增强颗粒的过渡层来强化镀层界面的复合材料金属化方法。对金属化后的玻璃纤维/环氧树脂复合材料试件采用拉伸试验法测量镀层的结合强度,并通过截面和断面的显微观测,分析了增强颗粒对于镀层界面的强化机制;同时获得了玻璃纤维/环氧树脂复合材料表面粗糙度和增强颗粒质量分数对含有过渡层的镀层结合强度的影响规律。结果表明:采用上述金属化方法可以显著提高镀层的界面强度,与传统的金属化工艺制备试件相比,玻璃纤维/环氧树脂复合材料在不同表面粗糙度下,镀层结合强度平均提高161%;同时,镀层的结合强度随着增强颗粒质量分数的增加,呈现先增大后减小的趋势,当增强颗粒的质量分数为50%时,镀层的结合强度达到最大。