Dynamic Tension Control and Dobby Shedding Parameters for Flax Warps
Active tension control and asymmetrical dobby dwell minimize stress spikes on low-stretch flax warps to prevent end breaks and starting marks.
Whip Roll Dampening
Tension Cushioning
Loom backrests must absorb the sudden increases in warp tension that occur when the harnesses open and when the reed beats up the yarn. The whip roll dampening refers to the mechanical or hydraulic resistance applied to the oscillating backrest roller to smooth out these tension spikes. This shock-absorbing action protects the warp yarns from being exposed to excessive dynamic forces during each cycle.
Mechanical Adjustment
Setting the correct amount of resistance requires adjusting the spring tension or the hydraulic valve settings based on the yarn characteristics and the loom speed. In linen production, the whip roll dampening must be carefully calibrated because flax yarn has very little inherent stretch and cannot easily absorb sudden shocks on its own. If the dampening is too soft, the whip roll will oscillate wildly, causing uneven tension that leads to start marks in the fabric.
When it is too stiff, the warp sheet is subjected to harsh, unmitigated forces that cause the yarn to snap during shedding.
Beam Protection
Mechanical components in the loom let-off system suffer less wear and tear when tension spikes are successfully cushioned. Correctly applied whip roll dampening extends the lifespan of the let-off gears, the harness frames and the backrest bearings. This reduction in machinery wear lowers long-term maintenance costs and increases the overall reliability of the loom.