The rubber mixing machine basically consists of three processes in the rubber mixing process:Roll wrapping, Eating powder, Refining and refining.
1. Roll wrapping
During mixing, there may be four possible situations where raw rubber appears on the roller of the open mill
The first situation occurs when the roller temperature is too low or the rubber is hard, causing the rubber to stay at the accumulated rubber and slide, unable to enter the roller gap, or only become fragments when forcibly pressed in.
The second situation occurs when the rubber is in a high elastic state, with both plastic flow and appropriate high elastic deformation. The rubber material is only wrapped around the front roller after passing through the roller spacing, which is beneficial for mixing operations and dispersion of the compounding agent in the rubber material.
The third situation occurs when the temperature is too high, the rubber fluidity increases, the intermolecular forces decrease, and the elasticity and strength decrease. At this time, the film cannot tightly wrap around the roller and form a bag like shape, resulting in roller detachment or breakage, and cannot be mixed.
The fourth situation occurs at higher temperatures, where the rubber changes from a highly elastic state to a viscous state, with almost no elasticity and strength, making it difficult to cut the rubber material. So, the temperature of the mixing should be controlled to keep the rubber material in good condition, which is conducive to the mixing process.
2. Eating powder
The powder eating stage refers to the process of mixing the compounding agent into the adhesive material. After the rubber roller is wrapped, in order to quickly mix the compounding agent into the rubber, a certain amount of accumulated glue should be retained at the upper end of the roller gap.
When adding the compounding agent, due to the continuous flipping and replacement of the accumulated glue, the compounding agent is carried into the wrinkles and grooves of the accumulated glue, and then into the roller gap.
During the process of eating noodles, the amount of accumulated glue must be moderate. When there is no accumulated glue or the amount of accumulated glue is too small, on the one hand, the compounding agent only relies on the shear force between the rear roller and the rubber to rub into the rubber material, and cannot penetrate deep into the inside of the rubber material, which affects the dispersion effect; On the other hand, powdered additives that have not been rubbed into the rubber will be squeezed into pieces by the rear roller and fall into the receiving tray. If it is a liquid additive, it will stick to the rear roller or fall onto the receiving tray, causing difficulty in mixing.
If there is an excessive accumulation of glue, some of the glue will rotate and roll at the upper end of the roller gap, rubber roller grinding machine,preventing it from entering the gap and making it difficult for the mixing agent to mix in. The amount of accumulated glue is often measured by the contact angle (or bite angle), which is generally between 32-45.
3. Refining and refining
The third stage of mixing is refining. Due to the high viscosity of rubber, during mixing, the rubber material only flows in the circumferential direction along the rotation direction of the open mill roller, without axial flow. Moreover, the rubber flowing in the circumferential direction is laminar. Therefore,internal mixer, the adhesive layer that closely adheres to the surface of the front roller at about 1/3 of the film thickness cannot flow and becomes a “dead layer” or “stagnant layer”lab kneader mixers.
In addition, the accumulated glue on the upper part of the roller gap will also form a partially wedge-shaped “reflux zone”. The above reasons all result in uneven dispersion of the compounding agent in the rubber material.
Therefore, it is necessary to go through multiple rounds of refining, cutting with left and right knives, rubber extrusion machine,rolling or triangular wrapping, thinning, etc., in order to break the dead layer and reflux area, make the mixing uniform, and ensure the quality and uniformity.
Post time: Oct-30-2024
