A comparative study on the performance of electronically- and mechanically controlled warp yarn let-off systems

rn recent years, several weaving machine makers have designed and developed the e lectronicallycontrolled warp yarn let-off system. The drive of this system is activated by an independentl y regulated e lectric motor which is controlled by an e lectronic regulator. Sulzer Ruti I designed a warp yarn let-off system with a variable speed electric motor for weaving machine model P7100. The speed of the motor is contro ll ed by detecting the displacement of the back rest roller by means of an inductive analogue sensor. Picanol 2 fo r GTM and PA T -A looms suggested a let-off mechani sm with an independently regulated e lectric motor whic h is controlled by an e lectronic regulator. Registering the warp tension can be achieved by detecting the displacement of the back rest roller by means of an e lectronic sensor. Other companies, viz. Somet, Toyoda and Tsudacoma, have also designed and app lied the e lectronic warp let-off system for their weavi ng mac hines . In sp ite of the extensive use of e lectronic warp let-off units instead of mechanical system, there are a few pape rs which consider the advantages in the working performance of e lectronic let-off compared to mechanical let-off units. Lunenschloss and Schlichter' suggested that the use of e lectronic warp let-off is ad vantageous over the use of mechanical let-off system in weaving filament sty le. They also analyzed the new possibilities in the des ign of warp yarn tension measuri ng e lements for their suitabili ty for use as warp let-off unit to control input quantities .