A STUDY OF MACHINE FACTORS THAT AFFECT THE FORMATION AND GEOMETRY OF FABRIC PRODUCED ON A TRICOT IsARP KNITTING MACHINE

This thesis is an account of an investigation into the machine conditions that affect the mechanism of loop formation and the fabric structure on a warp knitting tricot machine. The experimental work has been carried out on a ’Liba Excentra' industrial tricot knitting machine using 44 DTex polyester continuous filament yarns. Throughout the experiments a very wide range of structures and qualities were produced with erect loops and the knitting conditions such as run-in, run-in ratio, front and back bar tension. fabric tensions and the settings of the knitting elements to knit such structures were established. For the purpose of tension measurement, two sets of instruments were used, the ’Elmatex’ tension meter for average warp tensions and the ’Rothschild’ electronic yarn tension meter for cyclic tension variations. The fabric tension was measured by the ’Esotex’ fabric tension meter and the position of the knitting elements was determined by close-up photographs and dial indicators. It has been found that the tension ratio warps depends on the structure (ie, length of between front and back underlap on each bar) and the angle between the underlap and the course line. A loop model has been constructed which takes into account the forces applied by the take-up mechanism. The values calculated by this model provide a very good fit to the results obtained experimentally. From the relationships position of the sinkers and between the warp tension and the relative needles a better understanding of the mechanism of loop formation has been obtained including a description of the robbing-back phenomenon which has been shown to be as large as 80% of the loop as cast into the fabric. A new mechanical system to set the knitting elements to pre-set positions in accordance with the fabric quality has been developed and is described.

Name dc:type.qualificationname

PhD

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

De Montfort University

Year dc:date.issued

1980

Author dc:creator

• Raz, Shmuel

Licence

• https://dora.dmu.ac.uk/bitstreams/9e59ceec-fc00-4ab4-9d44-0fd9fb87ec1f/download