Airjet looms - have automatic device to reduce weft breaks on weft insertion

摘要

In regulating the weft insertion on an airjet loom, from a reel, the weft is brought through an accumulator to yarn guides and then by airjet is projected into the shed. The final speed of the weft being inserted is automatically controlled. The appts. is also claimed. ADVANTAGE - When tender yarn is used as weft, breakages occur, partic. between accumulator and main jet. The breakages are reduced by the devices employed. Weft wound around the barrel of the accumulator is pref. drawn by the main jet through a weft guide, and projected across the shed of the loom, assisted by intermediary jets, until the leading end is located, to form a fringe or selvedge. A shear then separates the weft at the shed entrance. It is found by means of tension measurement, that as the speed of weft insertion drops to nil, having reached the selvedge, the likelihood of a weft break increases in the region between the weft guide and the main jet. A sensor at the selvedge, detects the approach of the weft, and is coupled to a controller, which actuates a weft tension device at a point where it must suppress the sudden increase of drag on the weft, causing the breaks. The tension drag device may be mechanical, electro-magnetic or aerodynamic.