两种牦牛绒集聚纱性能的对比分析

探讨两种集聚纺装置纺制牦牛绒集聚纱和赛络集聚纱的成纱性能。分别采用网格圈式和空心罗拉式集聚纺装置纺制牦牛绒20.8tex集聚纱和16.7tex赛络集聚纱,并进行了性能对比测试。结果表明:纺制20.8tex牦牛绒集聚纱,两者毛羽水平相当,空心罗拉式集聚纺所纺纱强伸性能显著提高,条干均匀度略好;纺制16.7tex牦牛绒赛络集聚纱,空心罗拉式所纺纱强伸性显著提高,毛羽明显减少,条干均匀度显著改善。认为:实际生产中,可根据纺纱品种和质量要求,合理选择集聚纺装置和赛络纺工艺,能够纺制出性能较好,质量满足要求的牦牛绒纱。     

竹原纤维纱线直径系数的测定

竹纤维是一种前景广阔的新型绿色环保凉爽型纤维，用竹纤维制作的服装和服饰越来越受到人们的青睐，但缺少设计必须的直径系数数据。因此，文章采用显微镜投影法及电脑图像分析软件，对常用的竹原纤维纱线直径进行了测定，并阐述了不同张力及加捻系数对直径系数的影响，得到竹原纤维纱线的直径系数平均值为0．0355，可供纺织产品设计开发人员参考。     

超大牵伸集聚纺莱赛尔纱的工艺研究

探讨超大牵伸集聚纺纺莱赛尔纱的工艺配置。通过TH558型超大牵伸细纱机和FA507B型细纱机分别纺制莱赛尔9.8tex和莱赛尔14.8tex集聚纱,并对比了成纱质量;同时纺制了莱赛尔7.4tex纱,对TH558型细纱机牵伸后区有无压力棒情况下的不同中区牵伸倍数做了对比试验。试验表明:四罗拉三区超大牵伸纺出纱的条干、强力、毛羽数、粗细节等指标较好,但棉结数有所增加;纺制莱赛尔7.4tex集聚纱时,牵伸后区加装压力棒后纺纱质量较好,中区牵伸应控制在1.15倍~1.60倍。认为:四罗拉三区超大牵伸形式对纺制特细号纱有较好的适应性;牵伸后区加装压力棒可以明显改善成纱质量。     

锥型面粉预混合机螺旋叶片的数学模型及造型设计

用复合函数的方法推导出了锥型面粉营养强化预混合机外螺旋叶片的数学模型,探讨了不同给定条件对设计结果的影响,提出了进行参数化3D图像结果生成的算法,并公布了应用AutoCAD内的AutoLISP语言编写的实际程序清单.生成的3D图像结果表明,本文提出的算法正确、可行.     

半积极上置式泡轴送经装置的研制

通过三种色织泡泡纱泡轴送经装置的应用与研究，分析了第一、二种送经装置的使用效果及优缺点，指出了第三种－半积极上置式齿轮胶辊泡轴送经的优点和推广价值，为在普通织机上提高色织泡泡纱的布面质量提供了一种经济合理的新型送经装置，同时也为在剑杆织机上配套泡泡纱装置打下了良好的基础。     

Microstructures and properties of friction stir spot welded DP590 dual phase steel sheets

DP590 steel sheets were joined by friction stir spot welding using polycrystalline cubic boron nitride tool with an objective to produce bond diameters similar to conventional spot welding nuggets. A range of spindle rotation (400–2400 rev min^?1) and plunge speeds (0·03–3·8 mm s^?1) were exercised to attain defect free welds in 1·6 mm thick sheets. A bond diameter of 4t^1/2, alike minimum nugget diameter criteria for resistance spot welds, resulted in superior mechanical properties than conventional spot welds. The heat inputs corresponding to different welding parameters influenced the weld microstructure, including grain size, phases and their morphology. The bond diameter was higher for higher heat inputs. However, low heat input welds with weld time cycles ～4 s produced more refined microstructure and exhibited similar strengths even with reduced bond size. Plug type failure was associated with larger bond diameters (～7·1 mm), while interfacial failure was observed with smaller welds (～5·4 mm).     

平面三滚柱定心夹具主要结构参数及公差分析

针对使用带平面三滚柱自定心夹具的工件需自锁并能方便松开的要求,分析了夹具各结构参数的公差对工件内孔尺寸精度要求的影响程度,提出了滚柱直径和楔紧平面到心轴中心距的公差计算方法。得出如下结论：工件内孔尺寸必须满足一定的精度要求;内孔所需的精度等级不仅与滚柱和楔紧平面到心轴中心距离的制造精度有关,还与工件内径的大小有关,且内径尺寸越大,所需的精度等级越低,为带平面三滚柱自定心夹具设计提供参考。     

延长顶吹炉炉期的有效途径

顶吹炉的“一炉三段”直接炼铅工艺技术不仅资源利用效果良好,而且节能、环保,在国际上居领先水平。先进的工艺需要低成本的支撑,炉衬的成本在顶吹炉运行成本中占有举足轻重的地位。如果炉衬使用寿命短,导致炉期缩短,运行成本必然增加,影响到“一炉三段”的产业化应用。因此,改进顶吹炉的布料方式,保护炉衬,延长炉期,从而减少维修成本,提高成本效益,以达到延长炉寿的目的,顶吹炉综合效益才能充分体现出来。本文主要介绍了延长顶吹炉炉期的技术改造方法和实际运用的效果。     

大直径回转轴密封元件的性能研究

本文对大直径回转密封件沿轴向的压力分布、泄漏量随压力的变化规律进行了测试，并且利用有限元理论及流体动力润滑理论对密封件进行了理论计算，从而揭示了它的密封机理。     

On the Dynamics of Lubricated Cylindrical Roller Bearings,Part I: Evaluation of Stiffness and Damping Characteristics

The stiffness and damping coefficients of a single roller-to-race contact of lubricated cylindrical roller bearings are numerically evaluated using a linearized perturbation method for both elastohydrodynamic lubrication (EHL) finite and infinite contact theories. A steady-state pressure equation is solved by a multilevel method and the elastic deformation is evaluated with the multilevel multi-integration method. Dynamic pressures are obtained by solving a set of perturbed pressure equations and are used to calculate the stiffness and damping coefficients. The influence of various nondimensional parameters (load parameter, speed parameter, material parameter, edge radius, and geometrical parameter) on the stiffness and damping are studied. The results show that a finite line contact gives higher values of stiffness and damping coefficients compared to an infinite contact, particularly at higher load and lower speed values. Based on the numerically evaluated data, curve-fitted relations for the stiffness and damping coefficients of a single roller-to-race contact are developed that can be used in the dynamic analysis of rotor–bearing systems.