Lab two roll mill is mainly composed of roller, bearing, frame, cover, transmission device, distance adjusting device, lubrication system, roll temperature adjusting device and emergency brake device. Although the size of laboratory refiners is different, their basic structures are quite similar.
Four kinds of laboratory mills with different structures
1. Old Drive Opener
2. New Drive Type Opener
3. Double Motor Drive Opener
4. Opener with Rubber Turning Device
Influencing factors of open-up machine plasticizing:
1: Roll temperature: Roll temperature is low, raw rubber viscosity is high, shear force is large, plastic effect is good. Usually the temperature is controlled between 45 and 55 degrees. When the temperature is high, not only the effect of plasticity is poor, but also the plasticity will decrease gradually even if the required plasticity is reached, resulting in elastic recovery. This plasticity is called thermoplasticity or pseudoplasticity.
2: Roll spacing: At the same speed ratio, the roll spacing is small, the shear rate is large, the shear force is large, and the plasticizing effect is good. Moreover, when the roll distance is small, the film thickness is small, and the film is easy to cool, which makes the rubber material viscous and subject to shear force, the plasticizing effect is improved.
3: Molding time: The plasticity of raw rubber increased rapidly in the first 10-15 minutes, and then stabilized. In order to obtain a greater plasticity (over 0.5 Wilson), the segmented plasticizing method must be adopted. Each time period does not exceed 20 minutes, the lower part of the plastic is cooled, parked for 4-8 hours, and then the next part of the plastic is processed.
4: Glue loading: The glue filling capacity during plasticizing mainly depends on the specifications of the starter. Excessive glue loading, floating accumulation of glue, difficult to diverge heat, poor plastic effect, and strong labor. The efficiency decreases when the glue loading is too small. The heat generation of synthetic rubber is relatively high, so the amount of rubber loading should be reduced appropriately.
5: The use of chemical plasticizer can improve the plasticizing effect, shorten the plasticizing time and reduce the phenomenon of elastic recovery, but the plasticizing temperature should be increased appropriately.
