Design, function, and applications of high-retention doffer and worker wire

Abstract

The transfer of fiber from higher-speed rollers, licker-ins, breasts, or swifts, covered with forward-facing teeth, to relatively lower-speed doffers and workers with backward-facing teeth, is analyzed using the mechanics and geometry of the process. The analysis shows that the front angle of the doffer and worker teeth is too large to prevent fibers from slipping off as a result of the pull from the teeth of the swift. The capacity of the doffer and worker teeth to retain fiber is enhanced by cutting steps parallel to the base into the front edge of the tooth, effectively lowering the front angle of the tooth to zero degrees. Teeth with extremely low front angles support fibers until they are perpendicular to the doffer or worker, maximizing retention and transfer. Carding trials on worsted and non-woven cards in a pilot plant reveal benefits attributable to the new wire design. A survey of commercial non-woven processors using the high-efficiency wire on doffers and workers also identified various benefits.

Design of double teeth metallic card clothing for the high-efficiency carding process by computational fluid dynamics

“…Recent research related to the design of the worker's teeth for nonwovens also showed wear resistance improvement when a new structure was applied. 19 A simple experiment with some parameter variation of the double teeth card clothing was carried out by our team in the spinning mill, which supported the point of view that the life span of the double teeth card clothing increased by at least 50% on average without changing the material (Figure 15). Despite the possibility that the wear resistance could be influenced by the fiber distribution on a tooth by its structure, the in-depth relationship between the structure and wear resistance remains a mystery; this needs further analysis and practical testing.…”

Online Wear Analysis of Card Clothings

“…due to wear, can lead to poorer penetration into the fibre flock and therefore also to lower fibre resolution, which massively impairs the working ability of the clothing [6]. This has already been demonstrated in some studies [1,2], which observed the loss of sharpness of the teeth due to a rounding of the tips. Based on these investigations, special attention is paid to the tip of the teeth in this study.…”

“…The team was supported by the project partner Graf & Cie AG, Rapperswill-Jona, CH which provided technical support in wear evaluation and derived measures to optimize the clothings for processing of high-performance fibres. To improve the clothing and make it not only more efficient but also more resistant to wear, optimisation of the profile shape [1,3] or clothing surface [4] have been considered.…”

“…Interval replacement of card clothings due to wear is well known. The wear is caused by the processing of fibres and results in loss of sharpness of the teeth, which affects the fibre transport during carding and reduces the nonwoven fabric quality up to the inability to work [1]. The clothing exchange is routinely carried out at certain maintenance intervals.…”

“…Aim of the project was to prevent avoidable clothing changes by developing an online wear measurement system and to take a step towards industry 4.0. Before project start there have been approaches to check and evaluate the wear of clothings [1,2], but an online analysis had not yet been developed. The online analysis was developed by the project partner Faserinstitut Bremen e.V.…”