3. Raw material factors

1. Cause analysis
(1) The moisture and volatile content of natural rubber exceeds the standard
(2) The storage of chemical raw materials and additives, the addition of ingredients, etc. are affected by the increase in moisture.
(3) The steel cord is damp and the coated steel paste is not dry.
(4) The moisture regain rate of the fiber cord is high, the original thread is higher than 2%, and it is higher than 1% before rolling
2. Solutions
(1) After the natural rubber is cut, the bake-out measures should be taken to control the moisture and volatile content according to the standard. It is strictly forbidden to exceed the standard and reduce the moisture content in the original rubber.
(2) In the storage of chemical raw materials and additives, add moisture-proof measures. During the rainy season, rainy season, and foggy weather, it is especially necessary to help transportation, storage, processing and other links to avoid moisture and wetness of raw materials. The prepared raw materials are filled with plastic materials.
(3) Open the packaging of the steel cord 1 hour before use, keep the indoor humidity not exceeding the standard, avoid the steel cord from getting wet, and dry the steel cord after applying the glue.
(4) The fiber cord is heated and dried before calendering, and the moisture regain rate of the cord before entering the calender is less than 1%
4. Production operation
1. Cause analysis
(1) The temperature control of the roller temperature of the kneader, the temperature of the hot-melt supply and the temperature of the extrusion and discharge are not strict, and there are bubbles on the surface of the semi-finished parts.
(2) There is a lot of air in the pressing rubber cord fabric and the thread, which is difficult to discharge during molding and vulcanization.
(3) The thickness and width tolerances of the semi-finished parts are too large, and the weight tolerance is large, which affects the flow of rubber in the mold.
(4) During the pre-forming process, the multi-layered rubber compound is liable to generate air buoyancy, which may cause blistering in the rubber.
(5) The steel cord is only hung on the surface layer when dipping. The air content in the steel wire is high, and the gap between the steel wires is large. It is easy to produce air entrapment when attaching the film.
(6) The pressure is low during vulcanization, the density of the rubber is poor, and bubbles are easy to form
(7) When the temperature and time during vulcanization do not meet the process requirements, it will also cause under-sulfur bubbles
2. Solutions
(1) Control the temperature and capacity of the rollers of the open mill, and prevent the overheating of the rubber material to produce bubbles wrapped in the rubber that are difficult to remove.
(2) The calendered rubber cords follow multiple sets of cotton threads along the warp row to increase the exhaust effect between the rubber cords. The calendered rubber cord is added with a piercing bubble device before being wound, and the exhaust effect between the rubber cords is increased.
(3) Modify the design of the extrusion die plate to make the shape of the rubber material conducive to the die, strictly control the construction dimensions and tolerances of the semi-finished rubber material, and prevent the product from trapping air.
(4) When there are multiple layers of rubber material to be stacked during pre-molding, the exhaust valve is pressed out of the rubber material to reduce the phenomenon of air trapped easily between the rubber layers, or the bubble needle is used to pierce the surface bubble of the rubber material.
(5) The steel cord is improved from dipping glue and sticking film to extruding and covering, reducing the air content in the wire in the glue, and reducing the phenomenon of air trapping when sticking the film.
(6) Reasonably set the mold cavity pressure to ensure the vulcanization pressure, so that the rubber material flows and fills the mold cavity.
(7) Strictly control the production operation according to the specified vulcanization temperature and time, and change the manual control operation to the microcomputer group control production operation.
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