How to judge whether the temperature control system of spinning machine works normally?
Temperature sensor inspection
Accuracy test: Before the equipment is turned on, use a standard thermometer to calibrate the temperature sensor. Place the standard thermometer and temperature sensor in the same environment with known temperature, for example, put them together in a constant temperature water bath. If the reading error between the temperature sensor and the standard thermometer is within the allowable range (generally 1-2℃), it means that the temperature sensor itself is accurate. In the spinning machine, temperature sensors in different positions (such as in the spinning box, near the cooling device, etc.) need such inspection.
Stability check: During the operation of the spinning machine, continuously observe the reading changes of the temperature sensor. Under normal circumstances, the reading of the temperature sensor should be relatively stable, and there will be no unreasonable large fluctuations. For example, when the spinning box temperature is set at 280℃, the reading of the temperature sensor should fluctuate in a small range around 280℃ (the fluctuation range may be within 3℃). If there is an instantaneous jump of more than ten degrees, it may indicate that the temperature sensor is faulty or disturbed.
Inspection of heating or cooling equipment
Heating equipment: For heated spinning machines, such as equipment that maintains the temperature of spinning box by electric heating, check whether the heating element works normally. You can check whether the heating element is heating by observing whether the working indicator lamp (if any) of the heating element is on or using an infrared thermal imager. If the heating element does not generate heat, it may be caused by circuit failure, heating element damage and other reasons. In addition, it is also necessary to check whether the heating power can meet the heating requirements. For example, when the spinning box starts to heat up from room temperature, it should be able to reach the set temperature within a reasonable time (according to the equipment specification, it may generally be within 30-60 minutes). If the temperature rises too slowly, it may be that the heating power is insufficient or the heating element is partially damaged.
Cooling equipment: For air-cooled equipment, check whether the fan is running normally. It can be judged by feeling whether there is wind blowing out of the air outlet and measuring the wind speed with an anemometer. Under normal circumstances, after the fan is started, the airflow should be clearly felt at the outlet, and the wind speed should meet the design requirements of the equipment. For example, the design wind speed at the outlet of the cooling duct is 5-10m/s, and the actual measured value should be within this range. For water cooling equipment, check the circulation of cooling water. Observe whether there is water flowing through the cooling water pipeline, and measure the flow of cooling water with a flowmeter. If the cooling equipment can't work normally, the spinning temperature will be out of control. For example, if the cooling equipment fails in the later stage of spinning, the fiber temperature may be too high, which will affect the fiber quality.
Temperature control unit check
Comparison between the set value and the actual value: Set different temperature set values on the operation panel of the spinning machine, and observe whether the actual temperature can follow the change of the set value and stabilize near the set value. For example, if the spinning box temperature is set to 270℃, the system should be able to automatically control the heating or cooling equipment, so that the temperature will gradually rise and stabilize at around 270℃ (allowing a certain fluctuation range). If the deviation between the set value and the actual value is too large (for example, the deviation exceeds 5℃) and cannot be adjusted to the normal range, it may be that the parameters of the temperature control unit are set incorrectly or the control algorithm has problems.
Control parameter inspection: Check the parameter settings of the temperature control unit, such as proportional (P), integral (I) and differential (D) parameters (in case of PID controller). These parameters will affect the accuracy and stability of temperature control. Generally speaking, P parameter determines the response speed of control, I parameter is used to eliminate the steady-state error, and D parameter can improve the dynamic performance of the system. By consulting the equipment manual or consulting the equipment manufacturer, understand the correct parameter setting range and adjust it according to the actual situation. For example, if the temperature overshoot occurs (the actual temperature exceeds the set temperature and then drops), it may be necessary to appropriately reduce the P parameter; If the temperature stabilization time is too long, it may be necessary to adjust the I parameter to speed up the stabilization process.
Temperature uniformity inspection
Multi-point measurement: install multiple temperature sensors in key parts of the spinning machine (such as different positions inside the spinning box and different areas of the cooling device, etc.), or use portable temperature measuring equipment to carry out multi-point measurement at these positions. In the process of equipment operation, compare the temperature difference in different positions. For example, in the spinning box, the temperature difference between different corners should be within a small range (generally not more than 3-5℃). If the local temperature is too high or too low, it may lead to uneven heating of the spinning solution and affect the spinning quality. For cooling devices, such as cooling ducts, the cooling temperatures of fibers in different positions should be as uniform as possible to ensure the consistency of fiber properties.
