大功率风机专用高效电动机转轴的强度计算与分析

根据风机专用高效电动机的特性,对大功率电机转轴的强度进行精确校核计算,并对计算结果进行了分析。     

空心锭包覆纺纱的芯纱残留捻回及其应用

为探讨空心锭包覆纺纱过程中外包缠纱对芯纱的假捻作用与应用,以黑、白两色涤纶长丝纱组成双芯纱,黑色涤纶长丝纱为外包缠纱,纺制了不同纺纱工艺的包覆纱,分析了芯纱残留捻回的捻向和捻度特征以及锭速、引纱速度、芯纱张力对芯纱残留捻度的影响;对利用芯纱残留捻度纺制段彩纱的原理与段彩特征进行了探讨,并给出了应用实例。结果表明:外包缠纱对芯纱缠绕的假捻作用,会使芯纱上形成残留捻向变化、捻度不等的捻回分布;残留捻回的捻度随锭速的增大、引纱速度的降低、芯纱张力的减小而增大;利用芯纱残留捻回的片段呈色效应,可用异色芯纱纺制具有段彩外观的“纱/纱”复合段彩纱,这种段彩纱具有区别于常规段彩纱的“闪色”特征。     

混比与捻系数对Modal纤维纱强度的影响

将Modal纤维以不同捻系数纯纺及与细旦涤纶以不同混比混纺成纱，并对其成纱分别进行拉伸性能测试分析，探讨了Modal纯纺纱捻系数及Modal／细旦涤纶混纺纱的混纺比与成纱断裂强度之间的关系，确定了Modal纯纺纱的临界捻系数。     

降低简装绢丝捻度不匀率的实践与探讨

降低筒装绢丝捻度不匀率是绢纺行业的研究课题之一。本文联系生产实践，对简装绢丝捻度不匀率增大的原因进行了分析，并提出了降低抢度不匀率的有效途径和措施。     

并捻工艺对Coolmax复合纱性能的影响研究

研究了并捻张力、并捻捻度对Coolmax／棉并捻复合纱强伸性能、毛细芯吸效应的影响，试验结果表明Coolmax长丝与棉纱不同并捻张力搭配对复合纱强伸性能有显著影响，复合纱断裂强度、毛细管芯吸高度都有临界捻度。优选出DTY8.33tex／34f Coolmax长丝与JC9．7tex棉纱并捻复合纱线的并捻工艺为：Coolmax长丝并捻张力10eN，棉纱并捻张力20eN，S向并捻，复合纱线捻度为60捻／10cm。     

Modelling of yarn shrinkage due to washing

Yarn shrinkage due to washing is modelled using the idea of helical model of yarn. The derived theoretical relation between yarn shrinkage and yarn twist intensity is experimentally verified. It is proved that yarn shrinkage increases non-linearly with the increase in yarn twist intensity.     

Impact of high-speed draw frame and its preparatory on packing and related characteristics of ring spun yarn

Impact of draw frame delivery speed, coiler diameter of carding machine and card draft on packing density of yarn and related characteristics of ring spun yarn have been found to be very significant. With the increase in draw frame speed and coiler diameter of card, there is a decrease in helix twist, helix angle, helix diameter with the consequent increase in yarn packing density. However, with the increase in card draft, both helix twist and helix angle increase up to a certain level, whereas helix diameter increases steadily; the yarn packing density shows a decreasing trend. Yarn packing density is always higher at the middle position of the fibre than at the position of trailing or leading hooks. However, coefficient of variation (CV%) of yarn packing density at the centre position of fibre is the lowest followed by leading position and trailing position of the fibre.     

Anisotropy in wrinkle properties of woven fabric

In this paper, the wrinkle resistance of plain fabrics woven with weft yarn in S‐ and Z‐twist directions and at various twist levels in different test directions has been measured and then analysed. Results show that the wrinkle resistance increases as the weft yarn twist increases. The wrinkle properties of the fabric show that the direction of test has an obvious effect on the results and the wrinkle resistance depends on the method of folding such as face‐to‐face and back‐to‐back methods. The experimental results showed that there is anisotropy in wrinkle properties of the fabric made of yarns with different twist directions. When the fabric is folded face‐to‐face and the weft twist direction is S, the wrinkle resistance of fabric in various test directions shows a convex curvature, whereas when the same fabric is folded in a back‐to‐back manner then results show a linear curvature. This means that the wrinkle resistance of a fabric differs in various directions and in the method of folding (back‐to‐back or face‐to‐face) and shows an anisotropic wrinkle resistance nature.     

Study of yarn twist angle using numerical simulation

The twist angle is an important parameter of the yarn which determines the degree and shape of the filament’s deformation produced along their length. So, in this paper, a 3D numerical modelling of filaments assemblies has been developed. The twist behaviour of the multifilament was simulated using ABAQUS finite element package by modelling the yarns as 3D continuum elements. The distribution of filament helix angle according to the radial position of the yarn is evaluated. Results show that the helix angle draws near zero in the yarn axis but does not fall to zero in presence of migration, and becomes bigger as the filaments are positioned on the surface. Moreover, the twist angle is calculated for different twist level which proves that twist angle is highly affected by torsion level. The target of the research was to establish a relationship between twist angle, twist value and yarn linear density for a series of models varying in the filament radius, twist value and filament number.     

Yarn twist measurement using digital imaging

Digital image analysis techniques in the spatial and frequency domains for twist measurement of yarns are described. A spatial technique is developed to extract the twist angle through the analysis of the yarn core image. Then, a Fourier transformation technique is applied to yarn images to measure the orientation of the fibre on the yarn surface. Finally, a hybrid method that incorporates frequency domain filtering prior to spatial analysis is proposed. The trials show that spatial analysis is a fast method and can successfully predict the twist in the yarn. Fourier transformation technique is quite sensitive to the protruding fibres obstructing the yarn surface, which may result in measurements having high variations. For yarns having little amount of hairs protruding from the core, the results agreed reasonably well with actual twist levels. Frequency domain filtering in conjunction with the spatial analysis of the yarn surface is found to be superior in terms of accuracy. The twist values calculated using the more reliable diameter measurements with back-lit images together with twist angles from the front-lit images are found to be more accurate when compared with the actual values.