The printing machine drying room is used to dry the printed fabric. The main types of heat sources in the drying room include steam, thermal oil, gas, fuel oil, and electric heating
The most commonly used ones are steam and thermal oil. The temperature inside the drying room and its stability have a significant impact on the quality of printing. If the temperature is too low, the drying efficiency is low, the printing speed is slow, and if the temperature is too high, the color light after printing will change, affecting the printing effect. The temperature control system for steam heated drying rooms consists of a temperature probe (PT100 thermistor or thermocouple), a temperature control meter, and a steam type solenoid valve. The temperature control method generally adopts a two position on-off control mode. When the temperature is lower than the set temperature of the drying room, the solenoid valve opens and steam enters the heat exchanger inside the drying room, causing the drying room to start heating up; When the temperature reaches or exceeds the set temperature of the drying room, the solenoid valve closes, the steam stops entering the heat exchanger inside the drying room, and the drying room stops heating up.
A probing roller is used to tightly press against the edge of the printing tape, and a potentiometer is driven to rotate through a connecting rod. The potentiometer outputs an analog signal of 0-10V, which is sent to the analog acquisition port of the PLC. After internal conversion by the PLC, it is converted into a digital signal to control the action of the correction motor. The action position of the correction motor after the deviation of the guide belt can be set through the human-machine interface on the machine. Due to the continuous detection method using analog signals, it can also set an alarm and stop for the deviation limit of the printed tape guide, and has online detection function. When the potentiometer is damaged or disconnected, it can also stop and give an alarm.
For the drying room heated by thermal oil, its control system generally consists of a temperature control meter with PID regulation, a temperature probe (PT100 thermistor or thermocouple), and an electric three-way valve. As the temperature and flow rate of the thermal oil in the heating furnace are constant, controlling the temperature of the drying room requires controlling the flow rate of the thermal oil entering the drying room.
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