What are the good methods of the mill when mixing rubber?

Mixing with a mill is an early mixing method in the rubber industry. Compared with mixing with a mixer, the mixing of the open mill has high labor intensity, poor production efficiency, unsafe, polluted environment, etc., and the uniformity of mixing is poor, so it has tended to be gradually eliminated. However, the use of open mill mixing, greater flexibility, mixed rubber is suitable for small production scale, small rubber batch and many varieties of factories. For the production of some special rubber materials, such as sponge glue, hard glue, color glue, etc., it is particularly suitable for mixing with an open mill, so the current use of open mill mixing in small rubber factories still accounts for a certain proportion.

The third stage of refining and mixing is refining. Due to the large viscosity of rubber, the rubber material only produces circumferential flow along the rotation direction of the roller of the mill during mixing, but there is no axial flow, and the rubber flowing along the circumferential direction is only laminar flow, so the rubber layer close to the surface of the front roller at about 1/3 of the thickness of the film cannot produce flow and become a "dead layer" or "sluggish layer". In addition, the build-up of glue in the upper part of the roll seam creates a partial wedge-shaped "return zone". The above reasons make the compound in the rubber unevenly dispersed.

Due to the high viscosity of rubber, the fluidity of the rubber material near the surface of the roller is poor, and the shear force promotes the flow of rubber only laminar flow. About 1/3 of the thick film inner layer in contact with the roller surface cannot enter and form a "dead layer".

Mixing operation method of the open mill When the mixing operation of the open mill, the raw rubber, master glue or combined rubber are generally added along one end of the large tooth wheel, and then various compounds are added for mixing according to the prescribed dosing order. The dosing method during mixing is divided into two types according to the glue content of the formula: if the raw rubber content is high, the compound is added in the middle of the roller, and the mill is opened and the glue dosing method is adopted to maintain an appropriate amount of accumulated rubber between the two rollers; If the raw rubber content is low, the compound is added at one end's rubber change dosing method. Compounds, compounds, which are less used and carbon blacks that are polluting in high volume, are usually added in the form of masterpieces or pastes.

Mixing generally adopts a one-stage mixing method, but if it is natural rubber and uses a larger amount of synthetic rubber and a large amount of carbon black filling, the two-stage mixing method can be used to make the rubber and the compound mix more evenly.

When all the compounds are added, it is necessary to turn over and further mix the compound. The rubber mixing methods include manual rubber tapping method and mechanical knife cutting method. The manual tapping method generally adopts left and right cutting, twisting, triangular bag and cutting knife rolling. The mechanical cutting method is to install a mechanical cutter close to the front roller, cut along the surface of the roller to make the glue fall in the disc, and then send it to the roller and repeat several times. After the turning is completed, the roll pitch (4~5mm) is relaxed, and then the cutting method is used to supplement the turning method for 2~3 times before the next piece.