A further step in automation

Improving machine efficiency and the resulting increase in productivity were the driving factor that led again to a new DORNIER development. AutoWarp^®, the automatic rear shed adjustment system, not only satisfies both points but also improves fabric quality. The device is currently being introduced on the market.

The need to reduce costs and support faster production cycles is often a somewhat negative side effect of globalization. The pressure can be especially felt when producing standard articles of high quality with typically low margins, as well as with those fabrics dependent on fast changing fashion trends. The increasing shortage in qualified personnel available in the textile industry altogether has to be compensated at the same time.

Since this environment will probably not change in near future – if ever – the production machines have to be improved and adapted. DORNIER AutoWarp^®, the automatic rear shed setting system for DORNIER rapier and air-jet weaving machines, is such an adaption. It uses modern stepping motor technology to adjust the back-rest roll vertically and horizontally, the warp stop motion horizontally and vertically, as well as the tilt, to precise positions. All these settings can be made by pushing respective buttons on the machine’s Dialog Panel, either during a style change when the machine is stopped or even while the machine is running. Precise positions can be stored with the style master data. They remain reproducible as required for any other machine, for example.

Scientific investigations at the German Institutes of Textile Research in Denkendorf and Aachen revealed clearly the importance of correct rear shed settings. These tests show unequivocally that the relation of tension between lower and upper shed has a very strong influence on warp thread breaks. The curve in the graph demonstrates clearly that setting changes with positive or negative values increase warp thread break frequency. Only a relatively small setting tolerance is available to optimize warp thread breaks to the lowest level.

Stepping motor arrangement for automatic back-rest roll and warp stop motion adjustment

This optimum back-rest and warp stop motion setting is often not searched for during practical day-to-day work because of the lack of time of the technicians. An average standard setting is used and higher warp break frequencies are just accepted, either consciously or not.

Correct rear shed adjustments can have also a decisive effect on the surface appearance when producing sensitive fabrics.

Raising the back-rest roll position by 4 cm and tilting the warp stop motion by 2 cm eliminated the "cracky" appearance with visible reed marks to a great degree (see picture). In summary it can be safely stated, that productivity and quality are decisively improved when the rear shed adjustments are made with reproducible precision utilizing the AutoWarp^® automatic rear shed adjustment system.

Relation between warp tension and warp thread breaks

The single advantages are:

reduction in thread breaks and set-up times
style development with less waste and shorter evaluation times
reproducible settings and setting data availability
style optimization while machine is running
checking improvement of fabric appearance while machine runs

Influence on fabric appearance by rear shed changes
Influence on fabric appearance by rear shed changes

Automatic rear shed setting also reduces the workload for operators and makes the weaving machine easier to use. The data recorded can also serve for possible future simulation programs.

The current AutoWarp^® version is available as an optional on rapier and air-jet weaving machines up to 220 cm nominal width with standard type back-rest roll assemblies. An extension to cover larger machine widths and different back-rest roll configurations is in preparation.