1. Polishing characteristics
Polishing roller generally adopts iron roller, and the working principle of iron roller polishing is basically the same as that of iron roller grinding. It is still polishing and grinding, which is completed by the joint action of 5 processes including collision, polishing pressure, tumbling, axial conveying, and spraying water. But polishing is not to remove the whole bran layer, but to remove the fine bran powder and the fine starch grains raised on the rough surface. Polishing and grinding white from the way of work compared, there are the following differences:
① Low polishing pressure; (2) The fluid density of polished rice grains is small; ③ The rice leaves the iron roller faster when polishing; ④ Large polishing movement area per unit output. 3. Analysis of factors affecting the polishing effect of rice polishing machine
2. Rice-making process
At present, the commonly used rice-making process is grinding white - polishing white - spray water polishing. First, the white rice is crushed by grinding, and the brown rice is cut and ground by the sand roller. Then wipe away the remaining bran layer and bran powder to improve the finish and color of the rice grain surface. After polishing the rice, a small part of the bran powder remains on the concave surface and there is roughness. Then, the bran powder is polished by spraying water and grinding. At the same time, under the action of polishing pressure and associated friction temperature, the starch fine end is semi-gelatinized to form a smooth surface.
3.1 Polishing pressure
The polishing pressure is established by the speed and collision force of rice grains in the polishing chamber. There are many factors that affect the whitening pressure, but the polishing pressure can be adjusted and controlled through the pressure door at the outlet of the polishing chamber. The polishing pressure is large, the collision movement is violent, and the crushing after polishing is much. The polishing pressure is small, the collision movement is relaxed, and the crushing after polishing is less. Therefore, the polishing pressure should be small, but the polishing pressure is too small, it will affect the process effect. The general polishing pressure is about 400-700g/cm2.