In the production, there will be “water wave” and “shun […]
In the production, there will be “water wave” and “shun” in the conveyor belt. This phenomenon is mainly caused by uneven vulcanization of the conveyor belt. The thermal dimensional stability of the EP canvas at high temperature and the vulcanization in the conveyor belt Tension in the process is a key factor
Fiber structure and properties
For NN or EP industrial yarns, the fiber state inside the fiber tends to curl. When spinning, it uses high tension at high temperatures and holds it until the fiber cools to allow the molecules to be pulled down at high temperatures and fixed during cooling. However, if heated again, it will again shrink above the glass transition temperature (about 100 degrees) and the amount of shrinkage will depend entirely on the amount of tension the material is subjected to in the original heat treatment. Therefore, the high-tension cooling fiber after stretching has good molecular flatness, which means high strength, low elongation and high heat shrinkage; low tension cooling fiber after stretching has poor flatness and thus low strength. High elongation and low shrinkage. If the same fiber is heat treated at different temperatures and tensions, fibers having different properties are obtained, and then under certain heat treatment conditions, the residual shrinkage of the fibers after free shrinkage of the fibers will be substantially the same.
Another feature of synthetic fibers is that at high temperatures, the material produces shrinkage forces. The greater the pre-tension, the greater the contraction force. Therefore, if vulcanized, excessive stretching will cause a large contraction force of the warp yarn to increase. The greater the tension, the greater the contraction force, which forces the weft yarn to deform further. If the warp yarns are tightly packed, if the EP conveyor belt needs to be widened, there is no room for widening during vulcanization, which can wrinkle the canvas and appear "avoid". After the material shrinks, the absolute strength does not differ much, but the relative intensity varies greatly. If the material shrinks heat, the material becomes thicker and the relative strength is greatly reduced. Other heat shrinkage rates are small, and the material thickness does not change without relative strength, so the fiber strength of low heat shrinkage tends to be low.
However, once the material undergoes the same heat treatment, after shrinkage, if the residual heat shrinkage is uniform, the relative strength is substantially the same. Therefore, when evaluating different matrix materials, the user should heat treat them under normal production process conditions to change the thermal shrinkage of the material and then evaluate its mechanical properties. Otherwise, the assessment is of little significance.