When sowing on a cotton cleaning machine, a large amount of impurities need to be removed, which is mainly achieved by the combination of dust grids. There are gaps between the dust bars of the dust grid, which can eliminate impurities. When excluding, it is required to remove as many impurities as possible while minimizing the amount of spun fibers that may fall. Therefore, it is necessary to fully utilize the differences in physical properties between fibers and impurities to achieve this requirement.
In the cotton cleaning machine, loosening is the primary condition for removing impurities. Loosening divides the cotton block into several small pieces, causing impurities to tend towards the surface of the cotton block and be easily detached from the original cotton. After being hit by a hitter, the raw cotton collides with the dust grid and produces vibration, which is beneficial for impurities to detach from the cotton block. When the raw cotton is repeatedly hit between the beater and the dust grid, because most impurities have greater elasticity than fibers, impurities may gain greater speed and detach from the cotton block.
Cotton chunks have a larger volume compared to impurities, so even the smallest cotton bundles are easily trapped by dust bars. Due to the suction force of the fan in front of the machine, most of the dust rods have a weak airflow that is replenished upwards. This airflow support force can prevent relatively light fibers from falling, while impurities with higher density overcome smaller air resistance and fall into the dust box at a higher speed. This is the principle of dust grid impurity removal in tombs.
The impurity removal ability of the dust grid can be adjusted by changing the installation angle and spacing of the dust rod, the spacing between the beater and the dust grid, the supplementary airflow at the bottom of the dust grid, etc. The impurity removal ability of the dust grid is also related to factors such as the feeding condition of raw cotton, the structure and speed of the beater, the size of the dust grid and the number of dust rods, the cross-sectional shape and size of the dust rod, etc.