Pleated or wrinkles effect in a fabric in the longitudinal or cross-direction or in diagonal direction as well as figure like folds, one describes these fabrics as pleated fabric or Plissé. The fabric formation includes 3 phases:-
• Middle fabric ‘inter-fabric’ weaving,
• Pleated length weaving,
• Formation of wrinkles.
Smooth pleated fabrics can be achieved by suitable folds structures as shown in Figs. 1, 2 which are more permanent than the wrinkles created afterward by pressing and fixing methods. Wrinkles can be achieved on one side or both sides of pleated fabrics. A ground warp needs to be much longer than tight warp as illustrated in Fig. 2, which must be more ensioned. For this reason, it is used two warp beams in the weaving machine and the weaving machine must be supplied with a special device.
Fig. 1: The appearance of a smooth pleated fabric
Fig. 2: The appearance of a tough pleated fabric
Wash proof pleated fabrics usually need to have more than 50% synthetic fibers such that the pleats do not fall out during wearing or washing. Pure cotton and wool fabrics also can be made pleated by applying synthetic resin finishes. It is now also possible to make permanent pleats during weaving without synthetic fibers or finishing.
It is expected that the relative cover of fold fabric less than inter-fabric, as the result of the interlacing between all warp yarns ‘‘ground and tight’’ and wefts in inter-fabric, on the other side the interlacing in fold fabric is just between the ground warp and wefts. The length of the inter-fabric must not be shorter than the half length of fold fabric, because the folds must not be overlapped with each other. Fig. illustrates cross-section in weft direction for the formation phases of a pleated fabric as follows:
A. Pleated fabric structure, the warp threads are arranged 1 ground yarn: 1 tight yarn,
B. Before the formation of wrinkles,
C. After the formation of wrinkles.
Points a and b represent the positions of the back rest and breast-beam
Fig. 3: Cross-section in weft direction for the formation of pleated fabric
Main methods for the production of pleated fabrics (Plissé)
The weaving machine of pleated fabrics must be equipped with two warp beams in addition to a device for displacement of the woven pleated fabric, or with variable beating up.
Weaving machine equipped with a special pleated device
At the beginning of this method both returning elements ‘back rest and breast-beam’ take the most far on the right lying position as illustrated at point A in Fig. 4 When the intended folds length is reached, they are farther on the left (B). The distance between the two limit points A and B is determined by the fold length.
After the last weft insertion within the fold length and with beginning of the next inter-fabric part, the pleated length is formed by returning back of the back rest and breast-beam into the starting position (A), at that moment the back rest pull the tight warp to the back position (A).
Fig. 4: Device for pleated fabrics weaving
The coordination of pleated fabric and take-up mechanism are shown in Fig.5. The height of the formed fold is equal to about half of the fold length before the backward-movement of the tight warp yarns.
Fig. 5: Movement coordination of pleated fabric and take-up device
Weaving machine equipped with a fabric displacement device
This method represents a wrinkles formation for the pleated fabrics on the weaving machine; it is somewhat old method as shown in Fig. 6. During the insertion of wrinkle wefts, the take-up device is stopped, at the same time, the fabric is held under tension by the bar 4 parallel to the breast-beam. This bar 4 is moved over the linkage 5 in direction of arrow. This movement is produced on the weaving machine supplied with a dobby device as follows: By means of the chain 6 the shift lever 7 is raised, whereby over the pawl 8 the ratchet gear 9 is turned around a certain amount. The change gear 9 is connected firmly with crank 10, at which sits the linkage 5. The ratchet gear 9 is secured by the pawl 11.
During this procedure the ground warp is let off. When the fold weaving is finished, the string 12 and the lever 13 therefore are raised by the dobby, and the slay 14 with the base 15 takes with its movement the hook-base of the lever 13 and the lever 16, whereby both pawls 8 and 11 are moved at the left side over the pin 17 and 18 at them. Now the rectangular lever 19 standing under feather-tension withdraws the ground fabric as well as tight warp so that the pleat is formed, and hereby the ground fabric can be woven without interruption.
Fig.6 : Weaving of pleated fabrics with variable beat-up of the slay
Fig. 7: Weaving of pleated fabrics by a shortening and lengthening of crank rod
In Fig. 7 the possibility of the formation of wrinkles on the weaving machine is represented by a shortening and lengthening of crank rod. During the fold weaving the string 1 and 2, which is controlled by dobby device, is lowered during this device. The activated-pawl 3 and the ratchet retaining-pawl 4 are in the engagement. The pawl 3 activates the ratchet gear 5 in the clockwise direction. Thus the bearing point 6 of the linkage 7 connected firmly with the ratchet gear is pushed upward, and the out-breakable crank shears 8 are expenditure-broken around a small bit, which means a shortening of the slay. The supporting rocker 9 is movable free on the shaft 10. When the ground fabric is to be woven, then the pawls 3 and 4 are out of contact with ratchet gear 5, and the linkage 7 is pulled by the spring 11 up to the attack on the support bearing 12, by what the maximum beating-movement is achieved again