Abstract:

Objective Combing is a key process in the ramie spinning system. However, the periodic unevenness in the combed web and sliver output by ramie combers not only severely restricts end product quality but also leads to an increase in the number of subsequent drawing passages, hindering improvements in production efficiency and cost control. Systematic research on this issue is of great significance for optimizing the combing process, realizing the integration of combing and drawing, and promoting the ramie spinning system towards higher production efficiency, better product quality, and lower cost.

Method The influence of process parameters, such as feed length and drafting gauge, on the weight distribution of fiber clusters were explored. A mathematical model for fiber clusters lapping into a web was constructed, and MatLab software was used to simulate and generate weight distribution curves as well as calculate unevenness characteristic, so as to conduct in-depth analysis on the correlation between effective output length and web uniformity. The method combining theoretical derivation and actual testing was adopted to verify the periodic wavelength characteristics of combed sliver unevenness.

Results Under the process condition where the effective output length of the comber was 6.7 cm, the study found that the feed length and drafting gauge have a significant impact on the weight distribution of fiber clusters and the uniformity of the web. Increasing the drafting gauge led to reduction of the length of fiber clusters and caused the overall weight distribution shifting toward the front end of the clusters, and increasing the feed length, on the other hand, resulted in length increase of fiber clusters, with weight distribution also shifting toward the front end. Further research indicated that when the feed length was fixed, increasing the drafting gauge would significantly improve the uniformity of the web, and similarly, with a fixed drafting gauge, increasing the feed length would also help to enhance the uniformity of the web. In particular, using a combination of 7.8 mm feed length and 49 mm drafting gauge was found effective to minimize the unevenness of the web.

It was also found in the study that the unevenness of the web was jointly affected by the weight distribution of fiber clusters and the effective output length. There were significant differences in the uniformity of the combed web under different effective output lengths. When the effective output length was approximately one-third of the length of the fiber clusters, the uniformity of the web remained at a relatively optimal level. However, it was necessary to combine the coordinated adjustment of the feed length and the drafting gauge to approach the theoretical optimal uniformity. In addition, both theoretical derivation and experimental verification confirmed that the periodic wavelength of the combed sliver unevenness was equal to the ratio of the delivery roller speed to the comber speed, with a maximum deviation of less than 0.6%. The above results clearly indicate the correlation characteristics between various process parameters and the unevenness of the web, as well as the internal connections and influence laws of periodic unevenness.

Conclusion This study clarifies the influence mechanism of combing process parameters, such as feed length and drafting gauge, on the weight distribution of fiber clusters and the unevenness of combed web, reveals the quantitative correlation between effective output length and the unevenness of combed web, and meanwhile elaborates the relationship between the periodic wavelength of combed sliver unevenness and the delivery roller speed as well as the comber speed. The research results provide reliable theoretical support for the accurate prediction and efficient regulation of the unevenness of combed web and combed sliver.

Key words: combing process, ramie combed sliver, periodic unevenness, fiber cluster, effective output length, feed length, drafting gauge