The closed-loop control of direct sampling control inside the roller wall is adopted to accurately control the roller body temperature, which provides effective guarantee for fiber heat treatment.
Heat treatment of artificial turf fiber with induction heating roller
Generally, there are 16 stations in the turf fiber production line, each station is composed of two upper and lower hot draft rollers, that is, after PP fiber passes through the front shower slot, the water containing fiber reaches the upper hot draft roller for several circles, and then after winding for several circles by the lower thermal drafting roller, it is wound by two hot rollers before winding.
The main functions of the heat treatment of the hot roll fiber after spinning are drying and heat treatment of the fiber. The process temperature is required to be 50 ~ 80 ℃. The linear velocity is 80 ~ 240m / min. In the production process, whether the hot roller can provide stable process temperature is the key to guarantee the quality of PP fiber.
At present, the heating roller of the production line is an electric heating roller. The resistance plate is used to heat the air and then radiate to exchange heat between the roller body and the fiber. The specific structure is as follows:
2. Existing technology defects:
The existing process has the following technology defects:
1). The temperature detection error is large so that the set temperature of roller surface cannot be reached in the production process .
There are two reasons for this: first, the resistance heating air is used to radiate the air to the roller shell, so the heat transfer efficiency is low. When the load (water containing fiber) is greater than the total heat radiation output of the resistance, the temperature of the roller body is far below the set temperature; second, because the probe is located in the air between the heating ring and the roller wall, the detected temperature is quite different from the actual temperature of the roller surface The temperature of roller surface cannot be accurately reflected. When the probe shows 80 ℃, the actual temperature of roller surface is only 20 ~ 30 ℃.
2). The uniformity of roller surface temperature is not good, which affects the product consistency
The roll shell is 5 mm thick cast aluminum with low heat capacity and without any temperature equalization measures. The temperature difference of the whole roll surface is large, which has a great impact on the product consistency.
3). Low heating efficiency and serious energy waste
The three ways of heat transfer are conduction, convection and radiation. Among them, the most efficient way of heat transfer is conduction, and radiation is the worst. The main heat transfer mode of the existing hot roller is radiation heating, which has low effective heat conduction utilization and serious waste of energy.
1). Temperature measurement is carried out inside the roller wall or on the surface of the roller body, which greatly improves the accuracy of the roller surface temperature sampling.
2). With the unique temperature equalizing technology of Lianjing, the temperature uniformity of the roller surface is greatly improved to ensure the product consistency. At the same time, the roller body thickness is appropriately increased to improve its heat capacity.
3). Induction heating or direct heating with electric heating rod is adopted to improve the heat utilization efficiency
Improve the efficiency of heat transfer, avoid the shortage of air heat transfer, from the original indirect heat transfer to direct heat transfer. The roller body is heated by electromagnetic induction or directly heated by electric heating wire.
Note: the thermal conductivity of air is about 0.031w / (m.k), and that of steel is 45 ~ 70W / (m.k). Therefore, using a new roller, the heat transfer efficiency will be greatly improved.
4. Product parameters：
45# steel、other steel alloy