Discussion on the factors affecting the polishing

2022-08-26
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Discussion on the factors affecting the polishing effect of rice

with the improvement of living standards, people's demand for high-quality refined rice is also increasing. Many domestic rice manufacturers have introduced rice polishing equipment to produce high-quality rice to obtain the best economic benefits. Therefore, it has become a consensus that the deep processing of rice is developing towards refinement. Generally, the surface finish of rice is divided into four levels, namely bright, bright, shiny and rough. In order to process bright rice with market competitiveness, we must improve the smoothness of rice, especially its polishing effect. Below we will make a preliminary discussion on this aspect

1. Choose a reasonable process

in order to process bright high-grade rice, in addition to good raw grain, the choice of processing process is also very important. The brown rice obtained by husking and rough rice separation not only contains imperfect grains and immature grains, but also mixed with fine impurities, grain ash and other impurities. Imperfect grains and immature grains are ground into broken rice and bran powder step by step after entering the rice machine. The bran powder is easy to adhere to the surface of rice grains and is not easy to remove, affecting the smoothness of rice grains. Fine impurities and grain ash are also easy to pollute the surface of rice grains. Therefore, before entering the rice mill, the thickness separator can be used to effectively remove imperfect grains, immature grains, fine impurities, grain ash and other impurities

even if the cable with single 1 structure is removed, there will be a single point of failure. The impurities mentioned above, but a certain amount of broken rice and bran powder will still be produced in the rice milling process. In order to avoid that the broken rice will be twice crushed into bran powder after entering the polishing machine, which will affect the polishing effect, it is necessary to add a screening before polishing. After screening out the broken rice and bran powder, it will enter the polishing machine. The following processing technology is suitable: brown rice → selection → milling → screening → polishing

2. Reasonably allocate the whitening accuracy of each pass

due to the different processing characteristics of Japonica and indica rice, the combination of rice milling machine and polishing machine is also different

processing Japonica Rice: sand roller rice machine → iron roller rice machine → iron roller humidifying rice machine → screening → polishing machine

processing indica rice: sand roller rice machine → sand roller rice machine → displacement analysis 0.001mm screening → polishing machine → polishing machine

generally, the whitening accuracy of the first sand roller should not be too large, otherwise, the first is to deepen the scratch on the surface of rice, which is difficult to repair during polishing; Second, the amount of broken rice increases, and it is easy to form bran powder when polishing and pressurization, which affects the polishing effect. When two passes are used, the effect of light first pass and heavy second pass is better. The first light polishing removes the bran powder and the surface of the rice grain has been repaired relatively completely. The second heavy polishing gelatinizes the starch on the surface of the rice grain to form a bright colloidal film. If the rice is thrown again, it is easy to stick the rice bran powder that has not been removed by the rice machine to the surface of rice grains. During the second light throwing, the bran powder is not easy to fall off and forms white spots on the surface of rice grains

3. Control of incoming rice temperature

from the actual situation of production and processing, cooling the materials before entering the last polishing machine has significantly improved the polishing effect. After the rice grains are cooled, the strength increases, so the pressure can be appropriately increased during polishing, the temperature in the machine can be increased, and the surface of the rice grains can be gelatinized to form a colloidal film. The polishing chamber of the polishing machine can be divided into two sections according to its primary and secondary functions. The front section is watered to soften the rice bran cortex, and the rear section is forced suction cooling, so that the bran powder separates from the rice grains and is discharged out of the machine. Therefore, the effect is more obvious when two series throwing machines are used

4. Selection and rational use of polishing machines

the current polishing machines in China are water assisted polishing, and the water adding methods include drip type, fan spray type and high-pressure air spray type, among which high-pressure air spray has a better effect. All stainless steel mirror iron rollers should be selected for the selection of polishing rollers, so that the polished rice grain surface is smooth and feels greasy

when operating the polishing machine, we should mainly grasp the flow, pressure, water addition and air volume. The flow is based on the rated flow, and increasing or too low will affect the polishing effect. The amount of water added is generally about 0.3% - 0.4% of the incoming flow. 7 inspection rules. During inspection, you can hold the rice tightly with your hand, which can form rice balls. It is advisable to plant it in 1 or 2 seconds or disperse it with a little bit. Too much water is easy to block the polishing room and is not conducive to storage. The adjustment of pressure is mainly to change the position of the weight at the discharge port so that the designed experimental machine has low efficiency. When the torque of the weight increases, the discharge resistance of the polishing machine increases and the polishing effect is strengthened. The polishing chamber works under full negative pressure. During polishing, a large amount of air enters the polishing chamber from the shaft end and takes away the bran powder and hot and humid air produced by polishing through the sieve hole. Of course, the negative pressure should not be too large, otherwise the rice grains are easy to sink at the bottom of the screen in the horizontal polishing machine, resulting in uneven polishing, the increase of broken rice, and even the phenomenon of stuffy car. (end)

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