The grains become brown rice after being hulled, and brown rice becomes rice after removing most of the cortex and part of the embryo. The surface of the rice grains of white rice still has a small amount of bran powder, which affects the appearance, quality, storage and taste of the prepared rice. This part of the chaff powder needs to be removed through the "polishing" process. Polishing is one of the key processes of clean rice processing. Because polishing can remove the bran powder on the surface of the rice grains, proper polishing can gelatinize the surface of the rice grains and present a certain brightness. At present, the rice polisher is the most used.
The main structures of various types of rice polishing machines are similar. They are mainly composed of a sprayed water part, a polishing part, a water supply system and a blower mechanism. The feeding device and the discharging device are also important devices of various types of rice polishing machines.
1. Spraying water part: The spraying water part is composed of nozzles, nozzle cleaners, water mixers, feeding spirals, stirring rollers, etc. When the materials pass through the flow meter, the flow is measured, thereby controlling the amount of water added.
2. Polishing part: The polishing part is the core part of the rice polishing machine, which is composed of a feeding screw, a polishing roller, an octagonal sieve tube composed of eight rice sieves, and a discharge pressure gate. The polishing roller is divided into iron roller and sand roller according to the nature of the material. The design should make it clear that the linear speed of the sand roller is higher than the linear speed of the iron roller (the linear speed of the iron roller is about 5m/s, the polishing pressure is higher, and the average value is 0.1MPa. The linear speed of the sand roller is about 15m/s, the polishing pressure is low, the average value is 0.02MPa).