Frictional movement of the warp wire in the heald eye during shedding

    During the weaving process, when the formation of the doup is an asymmetric doup, the warp wires and the heald eyes move relative to each other due to the differences in elongation and tension in the front and back parts of the doup, and thus the warp wires move very frequently, and the tension at the opening is quite high, so that this frictional movement often results in damage to or even rupture of the outer surface of the warp wires.

    Excluding the effect of friction, the movement of the warp wire in the heald eye is equal to the difference between the absolute elongation of the warp wires in front of and behind the doup frame at the time of opening. In fact, due to a certain amount of friction between the warp wires and the heald eye, the lateral gaps at the ends of the healds on the heald frames and the bending deformation of the healds, as well as the influence of the other parts of the warp wires and the fabric subjected to deformation in addition to the stranded part of the warp wires, the movement of the warp wires in the heald eye at the time of the opening is smaller than the above mentioned differential value. However, the movement of the warp wires in the heald eye will suddenly increase during weft beating due to the forward movement of the weaving mouth driven by the reed holder.

    From the above analysis, it can be seen that the shape of the doup frame and the movement of the heald frame have a large influence on the deformation, tension and friction movement of the warp wires. Therefore, the following section describes the determination of the height of the doup frame and the requirements for the movement of the heald.

The principle for determining the height of the gib is to ensure both a smooth passage of the sword belt through the gib and a minimum breakage of the warp wires during weaving.

    The height of the doup frame determines the warp wire tension during the opening process and the degree of frictional movement of the warp wire in the heald eye. If the notch height is too large, the tension on the warp wires and the friction against the heald eye increase dramatically. This will cause fatigue of the warp wires and increase the number of breaks. On the other hand, if the gib height is too small, it will be unfavorable for the operation of the sword belt, which is easy to rub against the warp wires in the gib and easy to produce skipped threads, wrong edges and other weaving defects near the side filaments. Therefore, the correct determination of the gib height is of particular importance.