Mixing with a open mill is an earlier mixing method in the rubber industry. Compared with mixing with an internal mixer, mixing with an open mixer is labor-intensive, low in production efficiency, unsafe, pollutes the environment, etc., and the mixing uniformity is poor. Therefore, it has tended to be gradually screened. However, mixing with an open mill has greater flexibility, and the mixed rubber is suitable for factories with small production scale, small batches of rubber materials and many varieties. For the production of some special rubber materials, such as sponge rubber, hard rubber, colored rubber, etc., it is particularly suitable to use open mills for mixing. Therefore, the use of open mills in small rubber factories still occupies a certain share.

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Analysis of the influence of open mill equipment manufacturers on the quality of compound mixing in open mill mixing equipment

The third stage of kneading is kneading. Due to the high viscosity of the rubber, the rubber material only moves in the circumferential direction along the rolling direction of the mill roll during mixing, but does not move in the axial direction, and the rubber moving in the circumferential direction is only laminar, so the thickness of the film is approximately 1/3 of the adhesive layer that is close to the surface of the front roller cannot move and becomes a "dead layer" or "sluggish layer", as shown in the figure. In addition, the build-up of glue in the upper part of the roll gap will also form part of the wedge-shaped "reflow zone". The above reasons all make the compounding agent in the rubber compound unevenly dispersed.

Due to the high viscosity of the rubber, the mobility of the rubber material in the vicinity of the outer surface of the roller is poor, and the shear force promotes the movement of the rubber to be only laminar flow. About 1/3 of the inner layer of the thick film in contact with the surface of the roller cannot enter the compounding agent, which constitutes a "dead layer".

Mixing operation method of open mill When mixing operation of open mill, generally, raw rubber, masterbatch or combined rubber are added along one end of the big cone, and then various compounding agents are added for mixing according to the prescribed dosing order. The dosing method during mixing is divided into two types according to the content of the formula: for those with high raw rubber content, the compounding agent is added in the center of the roller, and the mixing method is adopted to open the mill and adopt the method of pumping and dosing, so that an appropriate amount of accumulation is maintained between the two rollers. Rubber; for those with low raw rubber content, the compounding agent is added at one end, and the method of changing the rubber and adding medicine is adopted. Compounding agents with less amount of mixed rubber and carbon black with high flying pollution are usually added in the form of masterbatch or paste.

Generally, one-stage mixing method is used for mixing, but if it is a natural rubber compound with a large amount of synthetic rubber and a large amount of carbon black filling, a two-stage mixing method can be used to make the rubber and the compounding agent more uniformly mixed. .

When all the ingredients are added, it needs to be turned to make the rubber compound further mixed. The mixing methods of rubber mixing include manual tapping method and mechanical cutting method. The manual tapping method generally uses left and right cutting knives, folding and twisting, triangular wrapping and cutting knife rolling. The mechanical cutter method is to install a mechanical cutter near the front roller, cut along the surface of the roller to make the glue fall into the disc, and then send it between the rollers, repeating several times. After turning over, relax the roll distance (4-5mm), and then use the cut-and-drop method to supplement the turning for 2 to 3 times before unloading.