A process in chemical fiber production. The purpose is to obtain stress relaxation in the stretched fiber, which is beneficial to improving the crystallinity of the fiber and the stability of various properties, and reducing its boiling water shrinkage. The method is to keep the fiber under heated conditions for a certain period of time, so that the macromolecules constituting the fiber obtain sufficient activity energy, adjust the “position” of its chain segments, and make the energy of the fiber structure tend to the lowest. The shaping machine is a piece of equipment that completes the above process. Styling requires attention to many aspects.
Let’s talk about the three process elements of the stenter setting machine:
1. Temperature
Temperature is the most important factor affecting the quality of heat setting.
Because after the fabric is heat-set, the extent to which the original wrinkles are eliminated, the surface smoothness is improved, the dimensional thermal stability and other wearing properties of the fabric are all related to the heat setting. There is a close relationship between the setting temperature and the setting temperature.
2. Time
Setting time is another main process condition for heat setting. After the fabric enters the heating zone, the time required for heating and setting can be roughly divided into the following parts:
Heating time: After the fabric enters the heating zone, the surface of the fabric is heated to the setting temperature. time needed.
Heat penetration time: After the fabric surface reaches the setting temperature, the heat penetration time required to make the fibers in the inner and outer parts of the fabric have the same setting temperature.
Molecular adjustment time: After the fabric reaches the setting temperature, the time required for the molecules in the fiber to adjust according to the setting conditions.
Cooling time: The time required for the fabric to come out of the drying room and stabilize the size of the fabric for cooling.
The finalization time usually refers to the time required for the first three items, but does not include the fourth item. If the first item is regarded as a preheating effect, then the setting time only refers to the time required for the second and third items, that is, the time required for heat penetration and molecular adjustment.
The time required for heating and heat penetration depends on the performance of the heat source, the weight of the fabric per unit area, the thermal conductivity of the fiber and the moisture content of the fabric.
3. Tension
The tension on the fabric during the heat setting process has a significant impact on the setting quality, including The dimensional thermal stability, strength and elongation at break of the fabric all have a certain impact.
The thermal stability of the warp direction increases with the increase of the warp overfeed during shaping, while the thermal stability of the weft direction increases with the increase of the door width stretching degree. And decrease.
The average single yarn strength of the fabric after shaping is slightly higher than that of the unshaped fabric, and the change in the weft direction is more obvious than that in the warp direction.
The elongation at break of the fabric after setting decreases in the weft direction as the stretch increases, while in the warp direction it increases as the overfeed increases.
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