棉纺细纱后区牵伸型式的演变与发展(一)

The Evolvement and the Development of the Draft Types in the Rear Area in Cotton Spinning Process

为说明后区牵伸运用原则,从后区牵伸中纱条紧密度测定、有捻粗纱的匀伸作用、牵伸力与输出纱条不匀关系测定、不同牵伸分配、不同粗纱捻系数下前区牵伸力测定等方面分析,指出后区牵伸为前区主牵伸创造良好的牵伸条件;其实质是使喂入前区的牵伸纱条具有较均匀结构和必要紧密度,它产生的内摩擦力场强度与前区外摩擦力场强度分布相配合,共同形成胶圈牵伸良好而稳定的总摩擦力场强度分布,有利于成纱质量的提高;表明在此前提下,后区适当承担总牵伸的一部分可以减轻前区牵伸过大的负担,这就是后区牵伸运用原则。对罗拉直线牵伸、罗拉曲线牵伸和胶圈牵伸等各种后区牵伸型式进行了摩擦力场强度分布分析比较,指出单控制辊式VC型曲线牵伸是后区牵伸型式的重大突破和发展,可发挥前、后区牵伸潜力,其总牵伸能力达50～150倍,成为第三代大牵伸新水平,是后区牵伸型式技术进步的标志。

In order to introduce the drafting principle in the rear area,analysis is done to the following including the determination of the density of the sliver in the rear area,the uniform drafting of the twisted roving yarn in the rear area,the relationship of the drafting force in the rear area and the outcome of the sliver,the determination of the drafting force in the front area under different drafting allocation and different twisting factor.Conclusion is made that drafting in the rear area is the qualification of the main drafting in the front area.The enssential of the the small drafting force in the rear area is to produce the uniform structure and certain density of the sliver in the front area.The inner friction field distribution and the outer friction field distribution in the front area co-produces the good friction field distribution in general,thus a promotion of the yarn quality.It proves that proper drafting in the rear area can offset the overload of the drafting in the front area.This is the principle of the drafting in the rear area.Analysis is also done to the roller linear drafting,roller curvilinear drafting and the apron drafting regarding the friction field intensity.It is pointed out that the single roller controlled VC curvilinear drafting in the rear area is an important breakthrough and development of drafting types in the rear area,which can utilize the latent capacity both in the front area and the rear area with the general drafting multiples of 50～150.It symolizes the technology progress of drafting types in the rear area.