When the flour machine uses a flat sieve to lift the heart, a purer wheat heart can be obtained. According to the working principle of the flat screen, the material to be screened must move relative to the screen surface. As a result of this movement, the material is automatically classified, the small and heavy particles sink to the bottom, and the large and light material floats on the screen. The upper part, the rest is the middle layer.
It can be imagined that the material is divided into many plane layers, and they all make plane circular motion with a certain radius and a certain angular velocity. Due to the different properties of the material, the kinetic friction coefficient between the material and the screen surface is larger than that between the material and the material. Therefore, the upper material must have relative motion to the lower material, and it will be excluded from the sieve at a faster speed to become the material on the sieve. The materials in the lower layer also contain a lot of siftable materials. When they move relatively, they are not only affected by the frictional force of the sieve surface of the flour mill, but also the frictional resistance of the upper layer of materials. Therefore, the movement radius is small and the relative movement speed is slow. The time spent on the sieve surface is longer, which is easy to pass through the sieve hole and become the under-sieve material.