Nowadays, the production of rubber compound is mainly carried out by an internal mixer. In the internal mixer, the base rubber, compounding agents, and granular additives are uniformly dispersed and mixed, which is a more efficient mixing method. During operation, the gap between the rotor shaft diameter and the side wall of the mixing chamber is likely to cause the compounding agent to leak, so as to affect the mixing effect of the matrix glue and the compounding agent.
In order to prevent the occurrence of material leakage, people initially treated the fine and easy-to-spread components through oil film adhesion. However, due to the high pressure in the mixing chamber, the glue formed by the adhesion will be slowly squeezed out along the rotor shaft. Therefore, people added sealing rings at both ends of the rotor shaft, and then they became more and more perfect.
At present, the main sealing devices used on rubber mixers are as follows: end seal, labyrinth seal, reverse thread seal and packing seal, but these four sealing methods have many shortcomings: the commonly used end seal devices are in dense After the mixer has been running for a period of time, the sealing effect will decrease. This is because the compression ring cannot closely follow the movement of the rotating ring on the rotor during the operation of the mixer, resulting in gaps that cause the filling of fine materials and the sealing of the end face is not tight; After the labyrinth seal is used for a period of time, the powder compounding agent in the concave-convex ring will accumulate and cause leakage; although the reverse thread seal can push the compounding agent back into the mixing chamber under the action of axial force, it is used for a long time The back thread will wear out, and it still cannot achieve long-term sealing. Although the packing seal device is simple in structure and easy to use, the packing can be replaced by disassembling the gland, but the packing is severely worn and the life is not long. It needs to be replaced frequently, and only when the material is affected. The effect is better when pressed.
　　The gap between the rotor of the internal mixer and the mixing chamber should not exceed 1.5mm, usually 1.2-1.4mm.