From Paddy to Rice, Rice Hulling is Important

In the rice processing process, the process of removing the rice husk is called shelling, commonly known as hulling, for the shelling of machinery and equipment known as the hulling machine.

 

1.The Purpose and Requirement of Shelling

With paddy directly to rice (also known as rice to white), not only high energy consumption, low yield, low rate of rice, and finished rice quality is poor, such as broken rice, including the valley, low purity,etc. In addition, the by product utilization is also low, is not conducive to the rational use of rice resources. Therefore, in the rice mill factory now, after removing the impurities, the rice husk is removed first, and then the rice is made into pure brown rice.

At present, the mostly using method of hulling rice is applying mechanical force to the rice husk by hulling machine, the destruction of rice husk and the brown rice separately. Due to the differences between rice grains and the mechanical properties of rice hulls and the strength of rice grain, the current hulling machine is not yet able to hull all the rice once and will inevitably cause some encouragement to be damaged, such as broken, burnt and surface fluff. Therefore, in the rice shelling, to ensure a certain rate of shelling under the premise of the requirements and should try to keep the integrity of brown rice, reduce grain damage, reduce the consumption of materials and energy in order to improve the rate of rice and to ensure that the subsequent process of the process effect.

2.The Basic Method of Hulling Rice

According to the stress condition of rice shelling, the rice shelling method usually can be divided into three kinds of extruded shells: extrusion rubbing husking, end pressure rubbing husking and impact shell.

(1)Squeeze rubbing off the shell

Squeeze rubbing shell is the two sides of the rice by two different speed of movement of the face of the extrusion, the use of rubbing the role of the method to remove the shell.

Figure, grain on both sides were with the A, B two objects in contact, and by the two objects of the extrusion force Fp1, Fp2. A hypothetical object at a certain speed to move downward, a stationary object B, objects of friction F1 has always been on the grain, the grain downward, and B objects to produce friction F2 encourage upward, with a grain block together with the downward movement of objects. Thus, a pair of opposite frictional forces are produced on both sides of the grain. In the role of extrusion and friction, the customer produces tensile, shear, twist and other deformation, these changes are collectively referred to as rubbing effect. When the rubbing effect is greater than the combined strength of the husk, the chaff is torn off from the brown rice, so as to achieve the purpose of shelling.

(2)End pressure rubbing husking

End pressure rubbing and tearing shell is the two ends of the grain by two non-constant movement of the working surface of the extrusion, rubbing the role of the method to remove the glume.

In the figure, the grain is lying between A and B, and only one side is in contact with one of the objects (A body).Set the object to speed v1 as high-speed movement, B objects still.At this point, the grain is the role of two forces, one is to encourage the friction of the object F1, one is the grain movement generated by the inertial force Fk, two forces in the opposite direction, the formation of a pair of couple, thereby making the grain stand diagonally. When the tip of the grains after the reclining is in contact with the B object, both ends of the grain are subjected to the impact pressure Fp1 and Fp2 applied by the objects A and B, and are opposite to those of A and B. Of the friction force F1, F2. Under the combined action of pressure and friction, the chaff is destroyed, so as to achieve the purpose of shelling.

(3)The impact of shelling

Impact hulling refers to the high-speed movement of the grain and the fixed face of the collision and remove the rice husk method.

As the figure shown, the grain is accelerated by the mechanical force, with a certain angle of incidence to the surface of the stationary object, in the collision of the two moment, one end of the grain by a larger impact force Fp and friction F role , When these forces in the rice hull than the binding strength, the husk is destroyed, so as to achieve the purpose of shelling.