Study On The Relationship Between Dynamic Draft And Static Draft

Drawing is an important process in the spinning process, and it exists in many processes of spinning process. Furthermore,it also has a very close relationship with the quality of yarn. The drafting force is the key problem in the research of drafting theory.Drafting and its unevenness can not only reflect the smooth of the drawing process, also can indirectly reflect the quality of output yarn. Through the study on static draft simulation can indirectly research on the dynamic draft,which provides a theoretical basis for optimizing back technology.In this paper, using the drafting of on-line measurement system in dynamic drafting experiment and microcomputer control electronic universal material testing machine in static drafting study, then establishes a relation model between the tensile elongation in static drafting and drafting ratio in dynamic drafting in order to simulate the dynamic draft.In this paper, the following conclusions are drawn:(1) Based on the drafting of on-line measurement system, we can get the relationship between drafting force F and display reading x:F=0.5365 x by force analysis.(2) The sliver sample in cut and continuous state in tensile test are conducted, and then the test results of the sliver sample use the hypothesis test. Finally, we find the test result of the sliver in cut state is better. And through the experiment of different stretching speed, it is found that the tensile speed has a direct effect on the test result, so it is very important to select the appropriate tensile speed in the experiment.(3) In the dynamic drafting and static drafting of combed long cotton, although the sliver feeding quantity, rear roller distance, rear roller surface speed and moisture regain are different during test,the relationship between drafting force and drafting ratio graphic from dynamic drafting and static drafting has the similarity and the critical draw ratio are obtained about 1.2.And two curves with increasing drawing ratio of the trend is the same, with increasing drawing ratio first increases and then decreases.(4) In the dynamic drafting and static drafting of carded sliver, although the sliver feeding quantity, rear roller distance, rear roller surface speed and moisture regain are different during test,the relationship between drafting force and drafting ratio graphic from dynamic drafting andstatic drafting has the similarity and the critical draw ratio are obtained about 1.49~1.52.And two curves with increasing drawing ratio of the trend is the same, with increasing drawing ratio first increases and then decreases.