钢丝钳毛坯楔横轧成形压力的力能参数计算

中叙述了钢丝钳的工艺流程，介绍了楔横轧成形工艺的工艺参数及变形区参数，分析了楔横轧展宽区的金属变形情况及推导了变形区参数的工程计算公式。末对钢丝钳毛坯进行了实例计算。     

平板楔横轧工艺在羊角锤制坯上的应用

本介绍了平板式楔横轧的工艺特点，分析了羊角锤的变形工艺及设计了轧件。阐明了楔横轧模具的主要设计参数。计算了羊角锤楔横轧模具的孔型尺寸。通过羊角锤楔横轧制坯工艺的实践，分析及比较了新旧制坯工艺的技术经济。叙述了采用楔横轧工艺代替传统旧工艺的优点。     

楔横轧轧制有限元分析及无料头技术研究

楔横轧轧制技术以其高效、节能的特点受到越来越多的关注。结合有限元数值模拟技术,楔横轧工艺的基础理论得以深入研究,为消除轧件端部凹心指明了研究方向。依据凹心产生机理,通过多种途径实现了小料头、无料头轧制,促进了楔横轧技术的应用与推广。     

曲轴无飞边精密成形模具系统开发

为了解决曲轴模锻材料利用率低和能耗高的问题,基于有限元数值模拟技术,研究了热锻曲轴的无飞边精密成形工艺及模具系统。由于曲轴的几何结构单元主要为单缸曲轴,故首先给出了单缸曲轴的热锻工序,包括板式楔横轧、多向锻造和精锻。利用DEFORM 3D软件对曲轴的无飞边锻造过程进行全程数值模拟,结果表明:楔横轧工序中工件两端易突起,多向锻造中连杆颈圆角容易折叠,精锻中主轴颈圆角处容易折叠;楔横轧工序最大载荷为250 k N,多向锻造X向最大载荷为450 k N,精锻最大载荷为5 450 k N。最后将该技术推广到两缸曲轴和多缸曲轴,同样得到了良好的无飞边结果。     

工艺参数对楔横轧多楔成形轧件心部损伤的影响

采用热力耦合有限元模拟技术,针对某铝合金轴类件的模具进行精心设计,通过三维塑性有限元数值模拟,研究多楔成形模具工艺参数对轧件心部缺陷形成机理的研究。各楔工艺参数的设计是否合理将会严重地影响成形件的形状和质量,楔横轧轧制工艺参数对轧件心部损伤的影响是不一样的,轧制速度影响最大,成形角次之,展宽角最小。心部损伤随侧主楔成形角的增大而减小,随内侧楔成形角的增大而增大。     

特种轧制的结构分析与应用

特种轧制属于金属深加工技术范畴,金属深加工产品的开发应用提高了金属的利用率,同时又降低了成本。应用特种轧制的手段是获得金属制成品的最有效办法之一。特轧作为一种边缘学科,不论从技术装备上或是在经济效益上都显示了她的优越性和强大的生命力.本文着重对特轧的几个分支楔横轧,辊锻轧,摆动辊压和微型轧机的结构特点和技术参数的选择进行了详细的论述,对今后特种轧制的发展提供一点资料。     

展宽角对楔横轧单楔一次成形轧件缩颈缺陷的影响

为研究展宽角对大断面收缩率单楔一次成形轧件的颈缩质量影响规律,利用热力耦合有限元数值分析方法,结合铝合金连杆零件形状特点,对楔横轧大断面收缩率单楔一次成形过程工艺进行模拟,重点研究不同展宽角下轧件特征点的应力应变场和交变次数,根据模拟结果分析展宽角对轧件颈缩缺陷的影响。结果表明,在保证轧件旋转的条件下,相对较大的展宽角有利于改善颈缩缺陷。     

展宽角对二次楔横轧铝合金连杆预制坯心部质量的影响

采用热力耦合有限元模拟技术,分析不同展宽角工况下的轧件心部应力、应变和损伤状况。二次楔横轧的损伤经过了两道次的累积,7°展宽角的工况出现心部缺陷的可能性最大,9°展宽角的工况出现心部缺陷的可能性最小,损伤值变化趋势与应力应变相符,这是由于展宽角的增大使金属的径向流动变得均匀,但展宽角过大会影响轧件顺畅旋转,展宽角为9°时的轧件的心部损伤最小。     

基于有限元方法的带钢边部缺口在冷轧过程中的变形研究

使用有限元软件ABAQUS/Explicit,模拟了带钢边部缺口在冷轧过程中轧向应力集中以及变形情况。并改变压下率、轧制速度、摩擦系数和缺口长度等参数,分析其对缺口经冷轧后形状变化的影响。     

FK-5拉伸变形机生产DTY工艺参数

通过对Barmag FK-5拉伸变形机工艺参数的研究,探索了拉伸比、加工张力、D/Y比、上下热箱温度、超喂率、横动速度、干扰速率、行程修整时间等参数对产品质量的影响。     

数字人体模型中腰部剖面曲线参数化变形算法

针对基于特征的参数化人体造型方法在变形精度和个性化表现方面存在的问题,在深入分析人体部位造型和变化特点的基础上,提出一种新型的参数化人体造型和变形算法。首先,利用水平剖面横切获取人体模型的特征腰围围线,并引入人体特征尺寸参量,确定腰围围线上正面、背面和侧面的3个迭代初始轴和初始值;然后,利用角度加权平均计算出围线上各点的坐标,通过不断迭代实现腰围围线的变形;最后,在指定变形区内,根据其他相关围线的高度和腰围围线初始值,确定这些围线的迭代初始值,实现指定区域的其他围线变形,完成该区域的整体变形。研究结果表明,该数字化人体模型可依据指定特征尺寸,变形得到个性化人体模型。     

用于含 Z 向钢针立体织物的钢针置换夹持器设计

为解决人工逐根置换钢针以及传统夹持器在工作过程中存在的不足,设计了适用于钢针置换的专用钢针夹持器。该装置由楔形滑块、薄壁弹性夹持器等组成,通过楔形滑块对薄壁弹性夹持器产生压力使薄壁楔形夹持器发生弹性形变,转化为薄壁楔形夹持器对钢针的压力,以满足夹紧钢针的要求。这种专用钢针夹持器自动化程度高,定位精准,能快速实现夹紧与松弛;并对钢针夹持器工作过程进行受力分析,以保证钢针置换工作可靠、持续进行。为验证工作原理的可行性,设计了夹持置换钢针实验,结果表明,钢针夹持器原理可行,工作可靠,可达到使用要求。     

V带带轮轮槽角的设计计算

分析了V带在弯曲应力作用下楔角变化的规律,为使带楔面与轮槽更有效地接触,建立了V带带轮轮槽角与带轮基准直径的函数关系式。为V带带轮轮槽的设计提供了必要的理论依据,从而提出了延长带使用寿命的有效途径。     

低质人工林木材家具关键连接部位接合方式研究

为了提高低质人工林木材家具关键连接部位接合强度,改善家具关键部位易松动、变形等质量缺陷。本文基于低质人工林木材材性,通过实验研究与实践经验相结合,对"T"型和"L"型部位的各种榫接合方式进行了研究分析。提出采用张紧木楔、多榫接合、胶黏剂强化以及局部补强等措施,优化现有接合方式,增强低质人工林木材家具关键连接部位的力学性能。     

Modeling of Coupled Water Transport and Large Deformation During Dehydration of Apple Tissue

Water loss of fruit during storage has a large impact on fruit quality and shelf life and is essential to fruit drying. Dehydration of fruit tissues is often accompanied by large deformations. One-dimensional water transport and large deformation of cylindrical samples of apple tissue during dehydration were modeled by coupled mass transfer and mechanics and validated by calibrated X-ray CT measurements. Uni-axial compression–relaxation tests were carried out to determine the nonlinear viscoelastic properties of apple tissue. The Mooney–Rivlin and Yeoh hyperelastic potentials with three parameters were effective to reproduce the nonlinear behavior during the loading region. Maxwell model was successful to quantify the viscoelastic behavior of the tissue during stress relaxation. The nonlinear models were superior to linear elastic and viscoelastic models to predict deformation and water loss. The sensitivity of different model parameters using the nonlinear viscoelastic model using Yeoh hyperelastic potentials was studied. The model predictions proved to be more sensitive to water transport parameters than to the mechanical parameters. The large effect of relative humidity and temperature on the deformation of apple tissue was confirmed by this study. The validated model can be employed to better understand postharvest storage and drying processes of apple fruit and thus improve product quality in the cold chain.     

仿柞蚕丝聚酯纤维的形态结构和性能

采用熔融纺丝法将改性聚酯切片制成具有与柞蚕丝相似截面形态和结构性能的仿柞蚕丝聚酯纤维,分别探讨了仿柞蚕丝聚酯纤维和柞蚕丝纤维的截面形态和结构性能。研究结果表明仿柞蚕丝聚酯纤维与柞蚕丝纤维具有相似的扁平状截面形态,其截面形态的均匀性较好;仿柞蚕丝聚酯纤维的取向因子、弹性形变、回弹率、柔量、功系数、断裂强度和断裂伸长率都比柞蚕丝纤维的大,而其纤维的声模量和塑性形变比柞蚕丝的塑性形变小;随着定伸长率的增加,仿柞蚕丝聚酯纤维和柞蚕丝的弹性形变和回弹率都明显下降,但其塑性伸长有所增加。     

Effect of Freezing Rate on the Onion Cell Deformation Evaluated by Digital Image Correlation

Cell deformation induced by freezing is a phenomenon that is affecting food quality. In this paper, digital image correlation (DIC) was used to investigate the effect of freezing rate on onion cell deformation. In order to improve the measurement accuracy of DIC, a micro-scale speckle pattern was formed on the onion cell surface by evenly coating CuO nanoparticles before performing a freezing test. Then, freezing tests were carried out in three different frozen conditions and DIC analysis was performed. Test results show that the cell deformation is nonhomogenous. Relatively larger deformation usually occurs in the region near the cell wall, and the deformation in the central region of a cell is usually relatively smaller. Moreover, the range of the cell deformation field decreases with an increase in freezing rate. The relationship between the cell deformation and the freezing rate shows that a relatively smaller range of cell deformation corresponds to a better preservation quality of the onion. The deformation analysis presented in this study can be used to evaluate the quality of vegetables after being frozen.     

聚丙烯纺粘热轧法非织造布质量的内在影响因素分析

通过改变成网及固网的部分工艺,对不同生产条件下生产的产品性能,包括非织造布中的纤维直径进行了测试分析,研究了影响纺粘热轧法非织造布产品质量的内在因素。实验结果表明,在产品面密度不变时,力学性能随计量泵转速的提高而降低,硬挺度、透气性及非织造布中纤维直径随之增加,当泵转速达到一定值时出现断丝现象,产品的强力又开始下降;在泵转速一定时,面密度随轧机速度提高而下降,产品力学性能随之下降,透气性提高;在轧机速度一定时,产品面密度随泵转速提高而增大,力学性能、硬挺度随之增大,透气性下降。研究表明,网帘下的吸风量增加,会造成纤网中纤维变细,产品的力学性能上升,硬挺度与透气性下降;在其他条件不变时,随轧辊中油温的升高,产品的力学性能、硬挺度提高,透气性下降,但温度过高则会破坏纤维内部结构,其产品性能就会下降。     

Rheological Characterisation of Malaysian Varieties of Sweet Potato Doughs Using Large and Small Deformation Measurements

The rheological properties of sweet potato doughs at different mixing times were studied. In the large deformation extension test, extensibility parameters including dough length at fracture, measured, and actual forces acting on dough strips were obtained for calculating the stress-strain data. For the small deformation test, both storage and loss modulus of dough were studied. The extensibility of dough from sweet potato flour increased to its peak at five minutes mixing time before decreasing illustrating an optimum mixing time. The variety of VitAto which has a higher protein content of 5.7 g/100 g has higher values of all the extensibility parameters as compared to Bukit Naga and Okinawan. In terms of flow-behavior index, all sweet potato doughs displayed n values from 1.82 to 2.11, indicating strain hardening behaviors similar to wheat flour doughs. The small deformation tests were not able to identify the optimum mixing time, although in general, illustrated that sweet potato doughs were essentially elastic or recoverable. The Pearson correlations of large and small deformation tests showed that the rheological parameters were positively correlated among themselves in the evaluation of the effect of mixing time to rheological properties of sweet potato dough.     

柔性涤纶吊装捆绑带的耐动态疲劳性能

针对吊装捆绑带在循环使用过程中,因其力学性能和抗冲击性能易急剧恶化而影响其使用寿命的问题,通过对柔性涤纶吊装捆绑带分别进行多次循环定伸长和定载荷处理,对其耐疲劳性能进行了研究。结果表明:柔性涤纶吊装捆绑带在拉伸过程中呈现明显的胡克区、屈服区和增强区3个变化阶段;在较小形变(小于1%)或较小负载(小于断裂强力的10%)时,以急弹性形变为主;在较大形变或较大负载时,产生了破坏性的塑性形变,且不断累积;经过循环处理后,吊装捆绑带的断裂强力、断裂伸长率以及耐疲劳性能都急剧衰减,抗冲击性能下降显著,大大影响了其使用寿命。