The lubrication of the enameled wire
The curing reaction is very important, it is directly related to many properties of the enameled wire. If the curing is not enough, it will affect the flexibility, solvent resistance, scratch resistance, softening and breakdown of the enameled wire. Sometimes although the performance was good at that time, the stability of the paint film was poor. After a period of storage, the performance data decreased or even failed. If the curing is excessive, the paint film becomes brittle, and the flexibility and thermal shock decrease. Most enameled wires can be judged by the color of the paint film to determine the degree of curing, but because the enameled wires are baked many times, it is not comprehensive to judge only from the appearance. When the internal curing is not enough but the external curing is sufficient, the enameled wire has a good color, but the peelability is very poor. If the heat aging test is carried out, the paint film casing may be peeled off. Conversely, when the internal curing is good but the external curing is insufficient, the color of the enameled wire is also good, but the scratch resistance is poor. In the curing reaction, the high density of the solvent gas or the humidity in the gas will affect the conjunctival reaction, reduce the paint film strength of the enameled wire, and affect the scratch resistance.
The proper curing of the paint film mainly depends on the baking temperature and baking time. Under the same conditions, the baking temperature is high, and the curing degree is large; under the same baking temperature, the baking time is long and the curing degree is large. The baking time is also the line speed. When the furnace temperature is too high, the cross-linked polymer chains, especially the branched side chains, will break and crack to produce low molecular weight polymers with lower molecular weights, which will form smoke oil (old glue) after condensation. If low-molecular-weight substances are not well ventilated in the process of escaping, it may form old glue in the furnace mouth and chimney and produce old glue particles on the line, which will affect the quality of the product. The amount of old glue reflects the degree of pyrolysis of the polymer to a certain extent. If most of the paint-based resin is cracked, the mechanical, electrical and thermal properties of the paint film will be significantly reduced at this time. Varieties of enameled wire have different requirements for the curing procedure of the paint film. Most enameled wires are fully baked every time the paint is applied to make the paint film well cured. However, the polyimide enameled wire is completely different. If each paint is fully cured and cured during baking, the paint film of each paint will be layered and cannot be formed into a solid whole, and the strength of the paint film is very poor. , The scratch resistance is unqualified. This is because the polyimide paint film is fully cured into an infusible substance after baking, coupled with its poor adhesion characteristics, resulting in delamination of the paint film.
During the scratch resistance test, the paint film will be layered layer by layer. The layer is scratched. Therefore, when polyimine is baked, the paint film is basically cured but not fully cured. In some molecules of the paint film, there is still a small amount of base ends that have not reacted. When each paint baking is completed, the high temperature baking is finally carried out to make the paint The film is fully cured to form a relatively strong whole. 4. The solvent vapor and cracked low-molecular substances generated in the baking process of the enameled wire must be discharged from the furnace in time. The density of the solvent vapor and the humidity in the gas will affect the evaporation and curing during the baking process, and low-molecular-weight substances have an effect on the smoothness and brightness of the paint film. In addition, the concentration of solvent vapor is related to safety, so waste discharge is very important to product quality, safe production, and heat energy consumption. Considering product quality and safety production alone, the amount of waste discharged is larger, but a large amount of heat is taken away while discharging waste, so waste discharge should be appropriate. Catalytic combustion hot air circulation furnace usually discharges 20~30% of the hot air volume. The amount of waste discharged depends on the amount of solvent used, the humidity of the air, and the heat of the oven. For every 1kg of solvent used, about 40~50M3 (converted to room temperature) is required to discharge waste. From the heating of the furnace temperature, the scratch resistance of the enameled wire, and the gloss of the enameled wire, the amount of waste discharged can also be judged.
If the furnace temperature is turned off for a long time, but the temperature indication value is still high, it means that the heat generated by catalytic combustion is equal to or greater than the heat consumed by the oven, and the oven will be out of control at high temperature, and the waste discharge volume should be appropriately increased. If the furnace temperature is heated for a long time in the heating state, but the temperature indication is not high, it means that the heat consumption is too much, and it is likely that the waste volume is large. After the inspection is confirmed, the waste volume should be appropriately reduced. When the scratch resistance of the enameled wire is poor, it may be that the gas humidity in the furnace is too high, especially in humid weather in summer. The humidity in the air is very high. In addition, the moisture generated after the catalytic combustion of the solvent vapor makes the gas in the furnace The gas humidity is higher, and the amount of waste discharged should be increased. The dew point of the gas in the furnace is not more than 25℃. If the enameled wire has poor gloss and is not bright, it may also have a small amount of waste. This is because the cracked low-molecular substances are not discharged and attached to the surface of the paint film to make the paint film lose its luster.
Smoke is a common undesirable phenomenon on horizontal enamelled furnaces. According to the ventilation theory, the gas always flows from the point with high pressure to the point with low pressure. After the gas in the furnace is heated, the volume expands sharply and the pressure rises. When a positive pressure appears in the furnace, the furnace mouth will emit smoke, which can increase the exhaust air volume or reduce the air supply volume to restore the negative pressure zone. If there is only one end of the furnace mouth with smoke, it is because the air supply at this end is too large, and the local air pressure is higher than the atmospheric pressure, so that the supplementary air cannot enter the furnace from the furnace mouth, reducing the air supply volume and causing the local positive pressure to disappear. The temperature of the enameled wire coming out of the oven is very high, the paint film is very soft, and the strength is small. If it is not cooled in time, the paint film of the guide wheel will be damaged, which will affect the quality of the enameled wire. When the line speed is relatively slow, as long as there is a certain length of cooling section, the enameled wire can be naturally cooled. When the line speed is fast, the natural cooling cannot meet the requirements, and it must be forced to cool, otherwise the line speed cannot be increased. Forced air cooling is a widely used method. Use a blower to cool the wire in countercurrent through the air duct and cooler. Note that the air source must be used after purification to avoid blowing impurities and dust on the surface of the enameled wire, sticking to the paint film, and causing surface problems.
Although the water cooling effect is very good, it will affect the quality of the enameled wire, make the paint film moisture, and reduce the scratch resistance and solvent resistance of the paint film, so it is not suitable for use. Lubrication The lubrication of the enameled wire has a very large relationship with the tightness of the wire. The lubricant used in the enameled wire is required to make the surface of the enameled wire slippery, not harmful to the wire, not affecting the strength of the take-up reel, and not affecting the user's use. The ideal amount of oil applied is to achieve a slippery feel of the enameled wire, but no obvious oil can be seen on the hands. Quantitatively speaking, 1 gram of lubricating oil can be applied to the surface of 1M2 Enamelled Copper Wire. Common lubrication methods include felt oiling, cowhide oiling and roller oiling. In production, choose different lubrication methods and different lubricants to meet the different requirements of the enameled wire in the winding process. The purpose of winding and winding is to continuously, tightly and evenly wind the enameled wire onto the spool. It is required that the take-up mechanism has a stable transmission, low noise, proper tension and regular wire arrangement. In the quality problems of enameled wire, the proportion of returns due to poor wire collection and arranging is very large, which is mainly manifested in the high tension of the wire, the wire diameter is thinned or the wire reel burst; the wire tension is small, and the wire reel is broken. Loose lines cause chaotic lines, and uneven lines cause chaotic lines. Although most of these problems are caused by improper operation, it is necessary to take necessary measures in the process to bring convenience to the operators. The take-up tension is very important, which is mainly controlled by the operator's hand feeling.
