Warp Bridge and Warp Release Systems
- Created on Thursday, 13 July 2017 17:08
- Last Update: Tuesday, 18 January 2022 21:50
- Published on Thursday, 13 July 2017 17:08.
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Warp Bridge and Warp Release Systems
The warp beam is the part of the weaving machine in the form of a large reel where the warp threads are wrapped. The warp bridge is the weaving machine element that changes the direction of the yarns coming from the warp beam and transfers them to the fabric beam in parallel. It is in line with the fabric bridge. When the frames are aligned, the warp threads between the warp and fabric bridges are parallel to the ground. The warp bridge can be movable or fixed. Being mobile, that is, moving towards the inside of the machine during the opening of the shed, prevents the warp threads from breaking due to tension.
The warp bridge has three main tasks:
1- To direct the warp threads wrapped in the warp beam horizontally to the weaving area,
2-To keep the tensions constant by controlling the tension of the warp yarns,
3-It is to reduce yarn breaks by keeping the warp tension constant with back and forth movement at every moment of weaving formation. As the weaving is done, the warp threads must be transported from the warp beam. Warp release systems are systems that ensure the delivery of warp threads from the warp beam. As the wefts are tied to the warps, the warp length on the loom will be shortened, so the warp threads wrapped in the beam are left forward and the necessary warp lengths are fed to the weaving loom.
Warp release systems have three main tasks:
It is to provide the warp tension necessary for the formation of the fabric, to send the warp from the beam to the weaving zone as much as the woven fabric, to take some warp thread back to the warp zone when the shed is closed. Warp release varies according to the machine type. Previously (on old type looms), the negative warp release system was used, while today's technology applies the positive drive warp release system.
Negative Warp Release System
During weaving, the warp is emptied (released) in the thickness of the weft thrown by the weft. Therefore, negative means imprecise. Generally, weighted and spring systems work negatively. In this system, the rotation of the warp beam, that is, the warp release, is done with the help of warp tension. During the fabric formation, the tension of the warp threads that are pulled continuously increases gradually and this tension force turns the warp beam a little. Counterweights attached to the rope or band are attached to the outer edge of the warp beam. There is no warp tension measurement. The warp tension in the negative warp let-off system changes as a sudden decrease after a continuous increase. The period of this change is achieved by changing the location of the counterweight. However, any change in weights creates abrupt changes in warp tension. This may cause errors due to changes in the fabric line.
Positive Warp Release System
During weaving, the warp is emptied at a certain rate in each revolution of the machine, whether the weft is inserted or not. This unloaded amount is adjusted according to the weft density and remains constant until the end of the weaving. Therefore, positive systems usually consist of gears and levers. Warp threads must work under an equal tension during normal operation. This tension is very important for the lifting of the frames and the throwing of the shuttle. Positive warp release systems also take into account the warp tension on the machine. When there is any tension change in the warp, the warp bridge is affected by this change. The warp tension is regulated by transmitting the pressure of the yarns to the warp bridge to the warp release regulators through the levers attached to the bridge.