Open mill

• Workflow ：
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  • Pre-start preparation Operators should wear leather wrist guards, masks, and other protective equipment. Check if all parts of the equipment are functioning properly, such as checking for any foreign objects between the large and small gears and rollers, and checking the sensitivity and reliability of the emergency brake. At the same time, check the rubber material to avoid hard metal objects being put into the mill, causing a sudden increase in lateral pressure and damaging the equipment. In addition, preheat the rollers according to process requirements, and control the temperature rise speed, especially in winter when the temperature difference between inside and outside is large, more cautious operation is required. It is recommended to preheat the empty machine, and the temperature rise speed should be controlled at 1-2℃/min.
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  • Adjusting the roll gap Before starting, adjust the roll gap to maintain balance. Uneven adjustment of the roll gap at both ends will cause roller imbalance, easily damaging the equipment. This is strictly prohibited.
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  • Inspecting safety switches Ensure that the equipment's emergency stop device, safety door device, overload protection device, and other safety protection devices are intact and sensitive and reliable to ensure the safety of the operator during subsequent operations.
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  • Feeding rubber Put the prepared rubber or plastic raw materials between the two relatively rotating rollers. The materials will be rolled into the gap between the two rollers as the rollers rotate. For example, when mixing rubber, put the raw rubber in and start the subsequent plasticizing and other operations.
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  • Plasticizing (mixing) After the material enters the gap between the rollers, the two rollers rotate relatively to produce extrusion and shearing effects on the rubber (or plastic). Through repeated kneading, chemical reactions will break the molecular chains inside the rubber (or plastic), allowing various compounding agents to be fully dispersed, achieving the purpose of plasticizing or mixing. During this process, pay attention to the operating specifications, such as operating by first cutting the rubber sheet with a knife, then picking it up by hand; do not pull or tug hard before cutting; it is strictly forbidden to feed materials with one hand on the roller and receive materials with the other hand under the roller; if the material jumps or is difficult to roll, do not press the material with your hand.
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  • Adding powder (compounding agents), additives, and mixing According to the process requirements, add the corresponding powder (such as carbon black and other compounding agents), additives, etc., at the appropriate stage, and continue mixing to allow these additives to be evenly dispersed in the material. During the addition process, pay attention to controlling parameters such as the amount of piled-up rubber. The height of the piled-up rubber should generally not exceed the range of the contact angle (the contact angle is generally 32-45°). If the amount of piled-up rubber is too small, the added powder is not easily rubbed into the rubber and may even be pressed into thin sheets by the rollers and fall onto the bottom plate; if it is too large, the material will roll, and the powder will not be easily mixed in.
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  • Making triangular packages, thinning, and sheeting After sufficient mixing, operations such as making triangular packages and thinning should be carried out to break the dead layer and reflux zone, making the material mixing more uniform. Finally, sheet the material from the roller to complete the entire open mill workflow.
• Key components and functions ：
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  • Rollers These are the main working parts of the open mill, generally two hollow rollers or drilled rollers rotating inward in opposite directions. The one on the operator's side is called the front roller, which can be moved horizontally back and forth manually or electrically to adjust the roll gap to meet operational requirements; the rear roller is fixed and cannot be moved back and forth. The two rollers rotate relatively to produce extrusion and shearing effects on the material, so that the material in the gap between the rollers is subjected to strong mechanical action, thereby achieving mixing, plasticizing, and calendering purposes.
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  • Gap adjustment device Used to adjust the distance between the two rollers. According to the characteristics of the material, process requirements, and different operating stages, precisely adjust the size of the roll gap to ensure that the material receives appropriate extrusion and shearing force, achieving good mixing results.
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  • Heating and cooling system It can heat or cool the rollers to meet the temperature requirements of different materials at different stages. For example, preheating the rollers facilitates the initial input and plasticization of the material. When the roller temperature is found to be too high, cooling water can be appropriately introduced for cooling, but it should be noted that cooling should be gradual, preferably cooling the empty machine to avoid sudden cooling causing roller damage.
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  • Lubrication system Provides good lubrication conditions for various parts of the equipment that require lubrication (such as bearings and gears), reducing friction wear between parts, ensuring stable and efficient operation of the equipment, and extending the service life of the equipment.
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  • Transmission device Transmits power to the rollers, driving the rollers to rotate at the set speed and direction of rotation, ensuring a stable power supply during the operation of the open mill and ensuring the normal operation of the mixing operation.