On-line monitoring of the temperature of the steaming and wet drying cylinder
The steam supply and humidity drying cylinder is mainly composed of a cylinder body, an outer steam chamber and a steam inlet head. The specific monitoring scheme is: use a platinum thermal resistance to detect the internal temperature of the steam supply to the wet drying cylinder. When the temperature reaches the set temperature, the PLC controls the solenoid valve on the steam pipeline leading to the outer steam chamber to open to steam, so as to ensure the humidity. After the steam enters the outer layer steam chamber, it can be completely vaporized on the drying surface, so that the fabric can be evenly moistened without dripping water. In the past, the operators used their personal experience to operate the steam valve. Often, the time was short, or the quality of the steam was not good, and the heating temperature of the drying rack was not enough, which caused serious water dripping on the surface of the drying drum, which dripped onto the fabric and produced defective products.
On-line monitoring of fabric humidity before shrinking
There are three types of spray humidification devices used in the previous humidification unit: siphon gas-water nozzle, water suction pump and integrated nozzle combination, and booster pump and integrated nozzle combination. The water mist sprayed by these three types has a small amount of water droplets. The uniformity of the water mist is not very ideal for high-grade fabrics, and the spray volume cannot be adjusted according to the type of fabric. The humidity of the fabric depends entirely on the operator.
Online monitoring of fabric tension
There is a close relationship between the tension of the fabric and the shrinkage rate, especially between the wet unit and the rubber blanket. Users often adjust the fabric tension between the two units too high in order to eliminate the creases on both sides of the fabric, which affects the pre-shrinking effect, and also makes the wet-feeding motor in the state of power generation, which makes the inverter very easy to damage. In order to keep the tension constant, a tension detection roller is installed between the wet supply unit and the rubber blanket pre-shrinking unit, and the speed of the wet supply motor is controlled through the tension sensor.
When debugging on-site, firstly correct the zero point of the cloth guide roller; secondly, check whether the change in tension is consistent with the speed; thirdly, the display of tension must be consistent with the weighing unit used for zero point calibration; fourthly, frequency conversion The output voltage of the device is +/-lOV; finally, the PID control is realized by programming the PLC, and the appropriate PID parameters must be set, namely: PID sampling time 0.3s; PID gain 0.85; PID integration time 3s.
In the actual operation according to the above steps, when the zero point is corrected (that is, the zero point elbow is in a tension-free state, and the corresponding output voltage is OV), the cloth is passed into the cloth guide roller, and the zero point is detected. It is found that the zero point drifts, that is, the zero point is always An output voltage of -0·3V appears, corresponding to the displayed tension of -3kgf. In order to eliminate this phenomenon, the threading route can be flexibly changed on site, so that the zero drift can be solved. In addition, due to the different ways of feeding the fabric and the difference in dryness and wetness of the fabric, it is easy to cause a large change in tension. In this way, the original 25kgf tension corresponds to the output voltage of 1V, and 50kgf tension corresponds to the output voltage of 5V. Therefore, the online detection and control of the fabric achieves the desired effect.
